Fluorescent endoscope system enabling simultaneous achievement of normal light observation based on reflected light and fluorescence observation based on light with wavelengths in infrared spectrum

ABSTRACT

Excitation light for normal light observation with wavelengths in the visible spectrum, which is output from a lamp, and excitation light with wavelengths in the infrared spectrum for exciting a fluorescent substance characteristic of being accumulated readily in a lesion are irradiated simultaneously to a living tissue, to which the fluorescent substance has been administered, through an endoscope. Fluorescence components are separated from light stemming from the living tissue by means of a separator such as a dichroic mirror, introduced to a first imaging device, and then imaged. Light components with wavelengths in the visible spectrum are introduced to a second imaging device and then imaged. Signals representing the images are subjected to signal processing, whereby a video signal is produced. For better diagnosis, two images are displayed while, for example, one of the images is superimposed on the other.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a fluorescent endoscope systemfor simultaneously producing a reflected-light image depicted byreflected light with wavelengths in the visible spectrum and afluorescence image depicted by infrared radiation.

[0003] 2. Description of the Related Art

[0004] In recent years, an endoscope of which insertional part isinserted into a body cavity for the purpose of observing the alimentarycanal extending from the esophagus through the stomach to the small andlarge intestines or the trachea extending to the lung, or if necessary,of conducting various kinds of treatments using therapeutic instrumentsinserted into a therapeutic instrument channel has been put to use. Inparticular, an electronic endoscope having an electronic imaging devicesuch as a charge coupled device (CCD) has been widely adopted because animage can be displayed on a monitor and an operator of the endoscope islittle fatigued with manipulation.

[0005] By the way, a modality in which a fluorescent substance having anaffinity for a lesion such as a carcinoma is administered to a subjectto be examined in advance, excitation light for exciting the fluorescentsubstance is irradiated, and fluorescence emanating from the fluorescentsubstance is detected has attracted attention recently.

[0006] According to the modality, since intense fluorescence is radiatedfrom a lesion, the presence of the lesion can be judged from thebrightness of a fluorescence image. A system adopting the modality is,for example, a system, disclosed in Japanese Unexamined PatentPublication No. 59-40830, for detecting fluorescence emanating fromhematoporphyrin that is a fluorescent substance.

[0007] In the system disclosed in Japanese Unexamined Patent PublicationNo. 59-40830, control is given so that pulsed laser light for excitationand white light for normal observation can be irradiated selectively.Japanese Unexamined Patent Publication No. 7-59783 has disclosed asystem enabling observation of fluorescent substances such as chlorinand pheophorbide. In the system disclosed in Japanese Unexamined PatentPublication No. 7-59783, light suitable for exciting a fluorescentsubstance and light suitable for normal light observation (white light)are irradiated while being switched by a rotary filter.

[0008] For exciting fluorescent substances that have been employed inthe past, light with relatively short wavelengths of about 405 nm isirradiated. When light with the wavelengths is irradiated to a livingtissue, the living tissue itself fluoresces. Unless an apparatusexhibiting high spectroscopic precision such as a spectrometer isemployed, it is hard to distinguish self-fluorescence from fluorescenceemanating from a fluorescent substance.

[0009] Moreover, the transmittance of light with short wavelengthsrelative to a living tissue is so poor that a system usinghematoporphyrin to be excited by light with short wavelengths may missthe presence of a substance fluorescing in a deep subcutaneous region.

[0010] Moreover, in the prior art, excitation light and white light areirradiated while being switched temporally. Consequently, duringirradiation of excitation light, a fluorescence image alone can beproduced. During irradiation of while light, a normal light image alonecan be produced. There is a large difference in time between thefluorescence image and normal image.

OBJECTS AND SUMMARY OF THE INVENTION

[0011] The first object of the present invention is to provide afluorescent endoscope system enabling observation of a fluorescentsubstance that is excited to fluoresce by means of light withwavelengths in an infrared spectrum exhibiting good transmittancerelative to a living tissue, such as, an antibody labeled by indocyaninegreen, capable of nullifying the influence of self-fluorescence, andcapable of preventing a lesion in a deep subcutaneous region from beingmissed.

[0012] The second object of the present invention is to provide afluorescent endoscope system in which since a reflected-light imagedepicted by reflected light and a fluorescence image can be producedsimultaneously, there is no difference in time between the images, whichenables easy diagnose of a lesion, and of which endoscope can beoriented easily.

[0013] A fluorescent endoscope system comprises: an endoscope having anelongated insertional part capable of being inserted into a living body;a light source means for simultaneously irradiating excitation lightwith wavelengths in a first infrared spectrum, which causes afluorescent substance to be administered to a living tissue tofluoresce, and light with wavelengths in the visible spectrum; aseparating means for separating fluorescence with wavelengths in asecond infrared spectrum including at least part of the wavelengths ofthe fluorescent substance and different from the first infraredspectrum, from light stemming from the living tissue; a first imagingmeans for forming an image depicted by the fluorescence separated by theseparating means; and a second imaging means for forming an imagedepicted by light with wavelengths in the visible spectrum. Owing tothese components, self-fluorescence can be cut off together with lightwith wavelengths in the infrared spectrum that are longer than thewavelengths of the self-fluorescence. Fluorescence observation ofobserving an object using a fluorescent substance that is characteristicof good transmittance and ready accumulation in a lesion, such as, anantibody labeled by indocyanine green can be carried out. Fluorescenceemanating from a lesion in a deep subcutaneous region in which thefluorescent substance is accumulated can be observed but will not bemissed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIGS. 1 to 7 relate to the first embodiment of the presentinvention;

[0015]FIG. 1 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the first embodiment;

[0016]FIG. 2 is a diagram showing the spectroscopic characteristic of abandpass filter concerning transmission;

[0017]FIG. 3 is a diagram showing the spectroscopic characteristic of adichroic mirror concerning transmission;

[0018]FIG. 4 is a diagram showing the spectroscopic characteristic of anexcitation light cutoff filter concerning of transmission;

[0019]FIG. 5 is a diagram showing the characteristic of an antibodylabeled by indocyanine green concerning excitation and fluorescence;

[0020]FIG. 6 is a diagram schematically showing a scene in which afluorescent substance that is an antibody labeled by indocyanine greenis dispersed;

[0021]FIGS. 7A to 7E are diagrams showing particular examples of animage displayed on a monitor;

[0022] FIGS. 8 to 10 relate to the second embodiment of the presentinvention;

[0023]FIG. 8 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the second embodiment;

[0024]FIG. 9 is a diagram showing the structure of a mosaic filter;

[0025]FIG. 10 is a diagram showing the spectroscopic characteristics ofthe mosaic filter concerning transmission;

[0026] FIGS. 11 to 13 relate to the third embodiment of the presentinvention;

[0027]FIG. 11 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the third embodiment;

[0028]FIG. 12 is a diagram showing the structure of an RGB rotaryfilter;

[0029]FIG. 13 is a diagram showing the spectroscopic characteristics ofthe RGB filter concerning transmission;

[0030] FIGS. 14 to 20 relate to the fourth embodiment of the presentinvention;

[0031]FIG. 14 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the fourth embodiment;

[0032]FIG. 15 is a diagram showing the structure of a spectrumrestriction rotary filter;

[0033]FIG. 16 is a diagram showing the spectroscopic characteristics ofa visible light transmission filter and infrared light transmissionfilter concerning transmission;

[0034]FIG. 17 is a diagram showing the spectroscopic characteristic ofan excitation light cutoff filter concerning transmission;

[0035]FIG. 18 is an explanatory diagram showing operations in normallight observation;

[0036]FIG. 19 is an explanatory diagram showing operations influorescence observation;

[0037]FIG. 20 is an explanatory diagram showing operations in normallight/fluorescence simultaneous observation;

[0038] FIGS. 21 to 25 relate to the fifth embodiment of the presentinvention;

[0039]FIG. 21 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the fifth embodiment;

[0040]FIG. 22 is a diagram showing the configuration of a pre-processingcircuit;

[0041]FIG. 23 is a diagram showing the configuration of a video signalprocessing circuit;

[0042]FIG. 24 is a diagram showing the characteristic of hemoglobinconcerning absorption;

[0043]FIG. 25 is an explanatory diagram showing an example of a screendisplay on a monitor when normal light/fluorescent marker observation isselected;

[0044] FIGS. 26 to 30 relate to the sixth embodiment;

[0045]FIG. 26 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the sixth embodiment;

[0046]FIG. 27 is a diagram showing the configuration of a video signalprocessing circuit;

[0047]FIG. 28 is a diagram showing the spectroscopic characteristic of asecond dichroic mirror concerning transmission;

[0048]FIG. 29 is a diagram showing an image displayed when fluorescencesynthesis observation is selected;

[0049]FIG. 30 is a diagram showing an image displayed when normallight/fluorescence two-screen observation is selected;

[0050] FIGS. 31 to 41 relate to the seventh embodiment of the presentinvention;

[0051]FIG. 31 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the seventh embodiment;

[0052]FIG. 32 is a diagram showing the structure of a spectrumrestriction rotary filter;

[0053]FIG. 33 is a diagram showing the spectroscopic characteristics ofthe spectrum restriction rotary filter concerning transmission;

[0054]FIG. 34 is a diagram showing the structure of an RGB rotaryfilter;

[0055]FIG. 35 is a diagram showing the spectroscopic characteristics ofthe RGB rotary filter concerning transmission;

[0056]FIG. 36 is a diagram showing the structure of a filter diaphragm;

[0057]FIG. 37 is a diagram showing the spectroscopic characteristic ofthe filter diaphragm concerning transmission;

[0058]FIG. 38 is a diagram showing the spectroscopic characteristic ofan excitation light cutoff filter concerning transmission;

[0059]FIG. 39 is an explanatory diagram concerning operations in normallight observation;

[0060]FIG. 40 is an explanatory diagram concerning operations influorescence observation;

[0061]FIG. 41 is an explanatory diagram concerning operations in normallight/fluorescence simultaneous observation;

[0062] FIGS. 42 to 46 relate to the eighth embodiment;

[0063]FIG. 42 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the eighth embodiment;

[0064]FIG. 43 is a diagram showing the structure of a parallel rotaryfilter;

[0065]FIG. 44 is a diagram showing the spectroscopic characteristics ofthe parallel rotary filter concerning transmission;

[0066]FIG. 45 is a diagram showing the structure of a liquid-crystaldiaphragm;

[0067]FIG. 46 is a diagram showing the configuration of an integrationcircuit;

[0068]FIG. 47 is an explanatory diagram concerning operations inaccordance with the ninth embodiment;

[0069] FIGS. 48 to 51 relate to the tenth embodiment of the presentinvention;

[0070]FIG. 48 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the tenth embodiment;

[0071]FIG. 49 is an explanatory diagram concerning operations in normallight observation;

[0072]FIG. 50 is an explanatory diagram concerning operations influorescence observation;

[0073]FIG. 51 is an explanatory diagram concerning operations in normallight/fluorescence simultaneous observation;

[0074] FIGS. 52 to 57 relate to the eleventh embodiment of the presentinvention;

[0075]FIG. 52 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the eleventh embodiment;

[0076]FIG. 53 is a diagram showing the structure of an RGB rotaryfilter;

[0077]FIG. 54 is a diagram showing the spectroscopic characteristics ofthe RGB rotary filter;

[0078]FIG. 55 is an explanatory diagram concerning operations in normallight observation;

[0079]FIG. 56 is an explanatory diagram concerning operations influorescence observation;

[0080]FIG. 57 is an explanatory diagram concerning operations in normallight/fluorescence simultaneous observation;

[0081] FIGS. 58 to 60 relate to the twelfth embodiment of the presentinvention;

[0082]FIG. 58 is a diagram showing the overall configuration of afluorescent endoscope system in accordance with the twelfth embodiment;

[0083]FIG. 59 is a diagram showing coefficients set in a spatial filterfor fluorescence observation; and

[0084]FIG. 60 is a diagram showing coefficients set in a spatial filterfor normal light observation.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0085] Embodiments of the present invention will be described withreference to the drawings below.

[0086] An object of an embodiment is to produce a visible-light imageand a fluorescence image depicted by infrared light emanating from anantibody labeled by indocyanine green with high image quality and withno difference in time between the images.

[0087] As shown in FIG. 1, a fluorescent endoscope system 1A inaccordance with the first embodiment of the present invention comprisesan endoscope 2A to be inserted into a body cavity for observation ordiagnosis of the inside of the body cavity, a light source apparatus 3Afor emitting light for observation and for excitation, a camera head 4Amounted on the endoscope 2A and having an imaging means therein, aprocessor 5A for processing a signal sent from the imaging means, amonitor 6 for displaying an image, a laser light source 7 forirradiating laser light for treatment, and an administration instrument20 for use in administering a fluorescent substance into a living bodythrough a forceps channel 36 in the endoscope 2A.

[0088] In this embodiment, an electronic endoscope having an imagingmeans is realized with a camera-mounted endoscope formed by mounting thefreely attachable and detachable camera head 4A on an eyepiece unit 98of the optical endoscope 2A.

[0089] The endoscope 2A has an elongated flexible insertional part 8 tobe inserted into a body cavity. A light guide fiber 9 over whichillumination light is propagated is run through the insertional part 8.A light guide connector 10 located at an incident end of the light guidefiber 9 to be placed near an operator's hand can be freely detachablyattached to the light source apparatus 3A.

[0090] The light source apparatus 3A includes a lamp 11 for radiatinglight with wavelengths in a spectrum ranging from the infrared spectrumincluding the wavelengths of excitation light to the visible spectrum, abandpass filter 12 located on the path of illumination light emanatingfrom the lamp 11 for restricting the wavelengths of light to betransmitted, an illumination light diaphragm 13 for restricting anamount of light, and a condenser 14 for concentrating light.

[0091] The bandpass filter 12 exhibits, as shown in FIG. 2, a nearlyflat characteristic of transmission in relation to a spectrum rangingfrom the visible spectrum to the infrared spectrum including thewavelengths of excitation light.

[0092] Light components with wavelengths in the spectrum ranging fromthe visible spectrum to the infrared spectrum is extracted from lightemanating from the lamp 11 by the bandpass filter 2, and supplied to thelight guide connector 10 of the endoscope 2A via the illumination lightdiaphragm 13 and condenser 14. The light is then emitted from a distalend of the light guide fiber locked in a distal part 15 of theinsertional part 8 to a living tissue 17 in a body cavity through anillumination lens 16 attached to an illumination window. Thus, theliving tissue 17 is illuminated with light with wavelengths in thevisible spectrum and with excitation light with wavelengths in theinfrared spectrum.

[0093] The distal part 15 has an observation window adjacently to theillumination window. An objective lens 18 is attached to the observationwindow. Reflected light and fluorescence stemming from the illuminatedliving tissue 17 fall on the objective lens, whereby images are formedat an image formation position of the objective lens. At the imageformation position, the distal end of an image guide fiber 19 serving asa transmitting means for transmitting optical images is located. Opticalimages formed on the distal end are transmitted to a back end of theimage guide fiber.

[0094] The camera head 4A has an image formation lens 21 opposed to theback end. A dichroic mirror 22 is located in the middle of an opticalaxis of the image formation lens 21 reaching an image formation positionof the image formation lens 21.

[0095] The characteristic of the dichroic mirror 22 concerningtransmission is, as shown in FIG. 3, such that the dichroic mirrortransmits visible-light components and reflects light components havinglonger wavelengths than the visible light.

[0096] Consequently, an optical image depicted by the visible-lightcomponents is formed at the image formation position toward which lighttransmitted by the dichroic mirror 22 is directed, and an optical imagedepicted by infrared-light components having longer wavelengths thanvisible light is formed at an image formation position toward whichlight reflected from the dichroic mirror 22 is directed.

[0097] An excitation light cutoff filter 23 for removingexcitation-light components from separated infrared light, and a firstCCD 25 are placed at the image formation position toward which lightreflected from the dichroic mirror 22 is directed with an imageintensifier 24 for amplifying infrared light between them. The first CCD25 receives light amplified by the image intensifier 24,photoelectrically converts the light, and thus produces an image signalrepresenting the infrared-light components.

[0098] The excitation light cutoff filter 23 is, as shown in FIG. 4,characteristic of transmitting light with wavelengths longer than thewavelengths of excitation light in the infrared spectrum. The spectrumincludes the wavelengths shown in FIG. 5 of fluorescence emanating froman antibody labeled by indocyanine green that is a fluorescentsubstance.

[0099] Excitation light is cut off by the excitation light cutoff filter23. Fluorescence components emanating from the fluorescent substance areintroduced to the CCD 25.

[0100] At the image formation position toward which light transmitted bythe dichroic mirror 22 is directed, a second CCD 26 for receiving redlight, a third CCD 27 for receiving green light, and a fourth CCD 28 forreceiving blue light are arranged with a dichroic prism 29 forseparating red light, green light, and blue light from visible lightplaced among the CCDs. The CCDs produce image signals representing thecolor light components.

[0101] The dichroic prism 29 has a blue reflection dichroic mirror layer29 a for selectively reflecting blue light located at an incident endthereof, and has a red reflection dichroic mirror layer 29 b forselectively reflecting red light located at a transmission end thereof.Owing to this structure, red light, green light, and blue light fall onthe second to fourth CCDs 26 to 28.

[0102] Image signals produced by the first to fourth CCDs 25 to 28 areinput to the processor 5A over signal lines. The processor 5A includes apre-processing circuit 31 for carrying out pre-processing such asamplification and white balance adjustment for the image signalsproduced by the first to fourth CCDs 25 to 28, an A/D conversion circuit32, a video signal processing circuit 33 for carrying out processingsuch as image enhancement, and a D/A conversion circuit 34.

[0103] The video signal processing circuit 33 includes an image memory33 a for storing component images of red, green, and blue produced bythe second to fourth CCDs 26 to 28, an image memory 33 b for storing aninfrared image produced by the first CCD 25, and a memory controlcircuit 33 c for controlling writing or reading in or from the imagememories 33 a and 33 b.

[0104] Also included is a display selection switch 33 d for use inselecting a display format according to which a visible light image andinfrared image are displayed on the monitor 6.

[0105] A video signal output from the D/A conversion circuit 34 is inputto the monitor 6, whereby the fluorescence image formed on the imageplane of the first CCD 25 and the visible light image formed on theimage planes of the second to fourth CCDs 26 to 28 can be displayed on adisplay screen of the monitor 6.

[0106] In this embodiment, a laser light source 7 for generating laserlight for laser therapy and a laser guide 35 for introducing the laserlight are included. The laser guide 35 is structured to be able to beinserted into the forceps channel 36 of the endoscope 2A.

[0107] In this embodiment, an antibody labeled by indocyanine green thathas an affinity for a lesion developing in the living tissue 17 (ischaracteristic of accumulating in the lesion) and that causes the livingtissue 17 to transmit excitation light with wavelengths in the infraredspectrum higher than the visible and ultraviolet spectra, and to emitfluorescence with wavelengths in the infrared spectrum is used as afluorescent substance to be administered to the living tissue 17.

[0108] Light with wavelengths including the wavelengths of the visiblespectrum and the wavelengths of excitation light for exciting thefluorescent substance is irradiated from an illumination means to theliving tissue 17. Light reflected from the living tissue 17 is mixedwith self-fluorescence of the living tissue 17 and fluorescence inducedby excitation light. Light components with wavelengths in the visiblespectrum and infrared spectrum are separated from the resultant light bymeans of the dichroic mirror 22. Using the light components withwavelengths in the visible spectrum, the second to fourth CCDs 26 to 28produce portions of a visible light image. The excitation light includedin the light with wavelengths in the infrared spectrum is cut off by theexcitation light cutoff filter 23. The first CCD 25 then produces afluorescence image depicted by fluorescence emanating from thefluorescent substance.

[0109] Next, the operations of the fluorescent endoscope system 1Ahaving the foregoing components will be described. An antibody labeledby indocyanine green is administered to the living tissue 17 prior to anexamination using the fluorescent endoscope system 1A.

[0110] Conventional fluorescent substances are usually administered to abody by performing intravenous injection. Another method ofadministering the antibody labeled by indocyanine green is such that asubject is asked to gulp a solution containing the antibody labeled byindocyanine green, or the antibody labeled by indocyanine green isdispersed directly into a living tissue inside a body using theendoscope 2A.

[0111] For example, a tube 20 a forming the administration instrument 20is, as shown in FIG. 6, inserted into a forceps port of the endoscope 2Aand run through the forceps channel. A movable part of a syringe 20 bconnected to the back end of the tube 20 a is thrust, thus dispersing afluorescent substance 20 c that is the solution containing the antibodylabeled by indocyanine green into the living tissue 17 through a smallhole at the distal end of the tube 20 a.

[0112] The antibody labeled by indocyanine green is, as described in thePCT WO96 23525, having an affinity for a lesion such as a carcinoma.When some time elapses after administration to the inside of a body, theantibody labeled by indocyanine green accumulates in the lesion.Moreover, the antibody labeled by indocyanine green is structuredsimilarly to indocyanine green (ICG) that has been employed in anexamination for studying the hepatic functions in the past. The antibodylabeled by indocyanine green is therefore quite safe for a living body.

[0113] When bonded with human IgG, the antibody labeled by indocyaninegreen exhibits the characteristic of excitation and fluorescence shownin FIG. 5. The peak wavelength of excitation light (indicated with adashed line) is about 770 nm, and the peak wavelength of fluorescence(indicated with a solid line) is about 810 nm. However, in practice,since the antibody labeled by indocyanine green is bonded with anothersubstance existent inside the body, the wavelengths become a bit longer.

[0114] Light with wavelengths of about 770 to 780 nm is irradiated tothe inside of a living body and light with wavelengths of about 810 to820 nm is detected, whereby it becomes apparent whether or not a lesionis present. Light passed by the bandpass filter 12 includes lightcomponents with wavelengths in the visible spectrum and with wavelengthsof about 770 to 780 nm, but does not include light components withwavelengths of about the peak wavelength of fluorescence (the bandpassfilter 12 passes light components with wavelengths in the visiblespectrum and wavelengths of a maximum of 800 nm). A filtercharacteristic of passing light with long wavelengths of 800 m or largeris, as shown in FIG. 4, adopted as the excitation light cutoff filter 23for extracting fluorescence components.

[0115] As long as excitation light with wavelengths of about 800 nm isused, it is unnecessary to take care of the influence ofself-fluorescence emanating from a living tissue itself. Moreover, sincethe light is little absorbed by hemoglobin or water, the light istransmitted efficiently by the living tissue. Excitation light cantherefore be irradiated to a region deeper than the mucosa of a livingtissue. Fluorescence stemming from the deep region may be transmitted bythe surface of the living tissue.

[0116] The lamp 11 in the light source apparatus 3A is a xenon lamp andradiates light with wavelengths in a spectrum including the visiblespectrum and the spectrum of wavelengths of excitation light forexciting an antibody labeled by indocyanine green. Light radiated fromthe lamp 11 is recomposed into light with wavelengths in a spectrumincluding the visible spectrum and the spectrum of wavelengths ofexcitation light while passing through the bandpass filter 12.

[0117] The bandpass filter 12 transmits red, green, and blue light raysand light with wavelengths of about 770 to 780 nm which excites anantibody labeled by indocyanine green, and cuts off light withwavelengths of 810 to 820 nm which is fluorescence components emanatingfrom the antibody labeled by indocyanine green.

[0118] Light passed by the bandpass filter 12 has an amount of lightthereof adjusted by the illumination light diaphragm 13, is concentratedby the condenser 14, and is then supplied to the light guide fiber 9 inthe endoscope 2A.

[0119] Light propagated over the light guide fiber 9 is irradiated fromthe distal end of the light guide fiber to the living tissue 17 throughthe illumination lens 16. The optical systems in the endoscope 2A andlight source apparatus 3A are designed to cope with the infraredspectrum. Irradiated light is absorbed and reflected by the livingtissue 17, and fluorescence is emitted from a lesion in which anantibody labeled by indocyanine green administered in advance isaccumulated.

[0120] The reflected light and fluorescence stemming from the livingtissue 17 form images on the distal end of the image guide fiber 19. Theimages are transferred to the back end of the image guide fiber 19, andinput to the camera head 4A mounted on the endoscope 2A through theimage formation lens 21.

[0121] Light incident on the camera head 4A has infrared-lightcomponents and visible-light components thereof separated therefrom bythe dichroic mirror 22. The infrared-light components reflected by thedichroic mirror 22 fall on the excitation light cutoff filter 23, areamplified by the image intensifier 24, and then detected by the firstCCD 25.

[0122] The excitation light cutoff filter 23 is designed to removeexcitation-light components for exciting an antibody labeled byindocyanine green and to transmit fluorescence components. Theexcitation light cutoff filter exhibits the spectroscopic characteristicof transmission shown in FIG. 4.

[0123] The image intensifier 24 is sensitive to wavelengths of about 350nm to 910 nm, and capable of detecting fluorescence emanating from anantibody labeled by indocyanine green. Thus, the first CCD 25 producesan image depicted by fluorescence components emanating from the antibodylabeled by indocyanine green.

[0124] Visible-light components transmitted by the dichroic mirror 22are input to a three-plate camera composed of the dichroic prism 29 andthree CCDs 26, 27, and 28. The dichroic prism 29.separates three lightcomponents of red, green, and blue from incident light, and routes thecomponents into the second CCD 26, third CCD 27, and fourth CCD 28.

[0125] Thus, the second, third, and fourth CCDs 26 to 28 produce normalvisible light (normal light) images. The first to fourth CCDs 25 to 28are driven synchronously by a CCD drive circuit that is not shown. EachCCD produces 30 frame images per second.

[0126] The electric signals produced by the CCDs 25 to 28 are input tothe pre-processing circuit 31 in the processor 5A. The gains of thesignals are controlled by an amplifier that is not shown, and the whitebalances of visible light images are adjusted by a white balancecorrection circuit that is not shown.

[0127] Thereafter, the signals are input to the A/D conversion circuit32 and converted into digital signals. The digital signals are input tothe video signal processing circuit 33, and stored temporarily in theimage memories 33 a and 33 b. Thereafter, the signals are subjected toimage processing such as image enhancement and noise elimination, andcontrolled for simultaneous display of a fluorescence image, normallight image, and character information.

[0128] The video signal processing circuit 33 can carry out theprocessing for displaying a fluorescence image and normal light imagewhile superposing the fluorescent image on the normal light image or theprocessing for normalizing a fluorescence image by carrying outinter-image computation for a normal light image and fluorescence image.Thus, an easily discernible fluorescence image can be produced togetherwith a normal light image.

[0129] A digital signal output from the video signal processing circuit33 is input to the D/A conversion circuit 34, converted into an analogsignal, and then output to the monitor 6. As for a display format on themonitor 6, it can be selected whether a normal light image andfluorescence image giving different visions of an object attained at thesame time instance are displayed side by side with the same size, thetwo images are displayed side by side with different sizes, the twoimages are displayed with one of the images superposed on the other, orimages produced by performing image processing on a fluorescence imageand normal light image are displayed. An operator can therefore viewboth a fluorescence image and normal light image simultaneously.

[0130] A fluorescence image and normal light image giving differentvisions of an object attained with no time difference between them canbe produced. Consequently, positioning a lesion can be carried outreadily with high precision. This will be found very useful fordiagnosis.

[0131]FIGS. 7A to 7E show images displayed on the monitor 6 according todisplay formats selected using the selection switch 33 d. FIG. 7A showsa display format in which a normal light image 6 a and fluorescenceimage 6 b giving different visions of an object attained at the sametime instant are displayed side by side with the same size. FIG. 7Bshows a display format in which the normal light image 6 a andfluorescence image 6 b giving different visions of an object attained atthe same time instant are displayed side by side with different sizes.FIG. 7C shows an image 6 c displayed by superposing a fluorescence imageon a normal light image giving one vision of an object attained at thesame time instant as the other vision thereof given by the fluorescenceimage. FIGS. 7D and 7E show the normal light image 6 a and fluorescenceimage 6 b respectively.

[0132] For laser therapy, laser light is emitted from the laser lightsource 7. The emitted laser light is irradiated to a lesion in theliving tissue 17 through the laser guide 35. The laser light source is asemiconductor laser. The wavelengths of laser light are matched with thewavelengths of excitation light for exciting an antibody labeled byindocyanine green. It will therefore not take place that a fluorescenceimage or normal light image is disturbed greatly by irradiation of laserlight. Moreover, since laser light is absorbed by the antibody labeledby indocyanine green, the lesion can be treated efficiently.

[0133] In this embodiment, the three-plate camera is employed. Asingle-plate camera having a mosaic filter placed on the face of the CCD26 or the like may be substituted for the three-plate camera. When thesingle-plate camera is used to detect normal light, cost can be reduced.

[0134] Instead of using a single lamp as a light source means forobservation, two or more light sources, for example, a halogen lamp fornormal light observation and a semiconductor laser or light-emittingdiode for use in exciting a fluorescent substance may be used incombination.

[0135] Moreover, since illumination light for exciting a fluorescentsubstance is well-transmitted by the living tissue 17, the light may beirradiated in vitro.

[0136] Moreover, the camera head 4A may not be employed. Alight-receiving device such as a CCD may be incorporated in theprocessor 5A. The endoscope 2A and processor 5A may be connected usingan optical connector. In this case, the endoscope 2A becomes morelightweight and compact.

[0137] For removing excitation light, the excitation light cutoff filter23 may not be placed in front of the image intensifier 24.Alternatively, a dichroic mirror characteristic of not reflecting anexcitation-light component may be used as the dichroic mirror 22.

[0138] This embodiment has the advantages described below.

[0139] According to this embodiment, a fluorescence image depicted bylight with wavelengths in the infrared spectrum emanating from anantibody labeled by indocyanine green can be viewed. When fluorescencewith long wavelengths can thus be observed, since self-fluorescence withlong wavelengths can be ignored almost completely, incorrect diagnosisderived from the self-fluorescence can be prevented. Moreover, sincefluorescence with long wavelengths and a high transmittance can beobserved, fluorescence stemming from a lesion in a deep submucosalregion can be detected. Consequently, it can be prevented effectivelythat the lesion in the deep submucosal region is missed.

[0140] Moreover, since a separating means for separating infraredfluorescence from visible light is included, a normal visible-lightimage and an infrared fluorescence image which give different visions ofan object attained exactly at the same time instant can be produced.Consequently, when an object moving violently is examined using anendoscope, or in particular, when a fluorescence image is superposed ona normal light image or the fluorescence image and normal light imageare subjected to inter-image computation, artifacts derived from adifference in position of the object between the images will not beproduced.

[0141] Moreover, when a visible light image and infrared fluorescenceimage which give different visions of an object attained at the sametime instant are displayed with, for example, one of the imagessuperposed on the other, if the distal portion of the endoscope 2A ismoved or a treatment is carried out using a therapeutic instrument runthrough the forceps channel, the contour or the like of the livingtissue 14 can be recognized by referencing the visible light image. Byreferencing the visible light image, therefore, the endoscope 2A can beoriented properly. This leads to a proper treatment. In other words,maneuverability can be improved.

[0142] Furthermore, since the four CCDs 25 to 28 are used to produce aninfrared fluorescence image, red image, green image, and blue image,high-quality images can be produced. The configuration of thisembodiment is especially suitable for the employment of high-definitionCCDs.

[0143] Next, the second embodiment of the present invention will bedescribed. An object of this embodiment is to provide a fluorescentendoscope system capable of producing a visible light image and aninfrared fluorescence image depicted by fluorescence emanating from anantibody labeled by indocyanine green, which give different visions ofan object attained with no time difference between them, and capable ofbeing realized by adopting a relatively compact imaging system.

[0144] This embodiment is configured similarly to the first embodiment.A difference will be described mainly. The same reference numerals willbe assigned to components having similar functions. The description ofthe components will be omitted.

[0145] A fluorescent endoscope system 1B in accordance with the secondembodiment shown in FIG. 8 is different from the fluorescent endoscopesystem 1A in the first embodiment in a point that an electronicendoscope 2B to be inserted into a body cavity for observation or thelike is substituted for the endoscope 2A and camera head 4A.

[0146] The electronic endoscope 2B has the elongated insertional part 8similarly to the optical endoscope 2A. The light guide fiber 9 is runthrough the insertional part 8, and the light guide connector 10 to besituated near an operator's hand is freely detachably attached to thelight source apparatus 3A. Light supplied from the light sourceapparatus 3A is propagated over the light guide fiber 9 and emitted fromthe distal end of the light guide fiber locked in the distal part 15 tothe living tissue 17 through the illumination lens 16.

[0147] An image of the living tissue 17 is formed on the objective lens18 attached to the observation window. A CCD 39 having a mosaic filter37 placed in front of the light-receiving plane of the CCD 39 is locatedat the image formation position of the objective lens.

[0148] The CCD 39 is connected to the processor 5A over a signal cable38 run through the insertional part 8. An image signal produced by theCCD 39 is input to the pre-processing circuit 31.

[0149] The mosaic filter 37 has, as shown in FIG. 9, transmission filterelements IR, R, G, and B, which separate infrared components IR, redvisible-light components R, green visible-light components G, and bluevisible-light components B, located in front of the pixels of the CCD39.

[0150]FIG. 10 shows the characteristics of the transmission filterelements concerning transmission. The transmission filter elements IRare characteristic of cutting off excitation light and passingfluorescence emanating from a fluorescent substance.

[0151] The pre-processing circuit 31 in the processor 5A extracts signalcomponents R, G, and B passed by the transmission filter elements R, G,and B from an image signal output from the CCD 39, and thus producescolor signals of red, green, and blue. Moreover, the pre-processingcircuit 31 produces a fluorescence image signal by extracting signalcomponents passed by the transmission filter elements IR.

[0152] The other components are identical to those in the firstembodiment. The description of the components will be omitted.

[0153] Next, the operation of this embodiment will be described.

[0154] Light radiated from the lamp 11 in the light source apparatus 3Ais supplied to the end of the light guide fiber 9, which is located nearan operator's hand, in the electronic endoscope 2B by way of thebandpass filter 12 and illumination light diaphragm 13, and irradiatedfrom the distal end of the light guide fiber 9 to the living tissue 17through the illumination lens 16. The bandpass filter 12 exhibits theaforesaid characteristic shown in FIG. 2.

[0155] Reflected light and fluorescence stemming from the living tissue17 fall on the objective lens 18 in the distal part 15 of the electronicendoscope 2B, and forms images on the light-receiving plane (imageplane) of the CCD 39 via the mosaic filter 37 located in front of theCCD 39.

[0156] The filter elements of the mosaic filter 37 are arranged as shownin FIG. 9, whereby infrared light components (IR), and red (R), green(G), and blue (B) visible-light components are separated from lightincident on the CCD 39. The filter elements of the mosaic filter 37exhibit the spectroscopic characteristics of transmission shown in FIG.10.

[0157] Visible-light components of red, green, and blue separated by themosaic filter 37 form normal visible-light images. Infrared componentsseparated by the mosaic filter 37 have wavelengths including thewavelengths of fluorescence but not including the wavelengths ofexcitation light. Only a fluorescence image representing the state of afluorescent substance can therefore be produced.

[0158] A signal output from the CCD 39 is input to the pre-processingcircuit 31, A/D conversion circuit 32, video signal processing circuit33, and D/A conversion circuit in the processor 5A in that order, andthen output to the monitor 6.

[0159] In this embodiment, visible-light components are divided into redcomponents, green components, and blue components. Alternatively, theymay be divided into cyan components, magenta components, and yellowcomponents.

[0160] Instead of using a single lamp as a light source means forobservation, two or more light sources, for example, a halogen lamp fornormal light observation and a laser diode or light-emitting diode foruse in exciting a fluorescent substance may be used in combination.

[0161] Illumination light for use in exciting a fluorescent substancemay be irradiated in vitro.

[0162] This embodiment has the advantages described below.

[0163] According to this embodiment, infrared fluorescence emanatingfrom an antibody labeled by indocyanine green can be observed. Moreover,since infrared fluorescence and visible light are separated from eachother by the mosaic filter 37, a normal visible-light image and infraredfluorescence image which express the states of objects at the same timeinstant can be produced. Moreover, both normal light and fluorescenceare observed using one imaging device. This results in a compact imagingsystem.

[0164] Next, the third embodiment of the present invention will bedescribed. An object of this embodiment is to produce a visible lightimage and an infrared fluorescence image depicted by fluorescenceemanating from an antibody labeled by indocyanine green, which expressthe states of objects attained with a very small time difference betweenthem.

[0165] The third embodiment is configured similarly to the firstembodiment. Only a difference will be described mainly. The samereference numerals will be assigned to components having similarfunctions. The description of the components will be omitted.

[0166] As shown in FIG. 11, a fluorescent endoscope system IC inaccordance with the third embodiment is different from the fluorescentendoscope system 1A in the first embodiment shown in FIG. 1 in a pointthat a light source apparatus 3B is substituted for the light sourceapparatus 3A and a camera head 4B is substituted for the camera head 4A.

[0167] The light source apparatus 3B has an RGB rotary filter 41 forrestricting wavelengths of light to be transmitted placed on an opticalpath linking the illumination light diaphragm 13 and condenser 14. TheRGB rotary filter 41 is driven to rotate by means of a motor 42.

[0168] The RGB rotary filter 41 has, as shown in FIG. 12, threeapertures in the circumferential direction of a light-interceptive disk.Red, green, and blue filters 43R, 43G, and 43B are fitted into theapertures. When driven by the motor 42, the RGB rotary filter rotates 30times per second. Thus, red, green, and blue light rays are selectivelytransmitted.

[0169] The red, green, and blue filters 43R, 43G, and 43B embedded inthe RGB rotary filter 41 exhibit the spectroscopic characteristics oftransmission shown in FIG. 13. Thus, the RGB rotary filter transmits anyof red, green, and blue light rays and also transmits infrared lightcontaining excitation light components for exciting an antibody labeledby indocyanine green.

[0170] Moreover, the bandpass filter 12 exhibits the characteristicshown in FIG. 2. When the bandpass filter 12 and RGB rotary filter 41are used in combination, one of red visible-light components, greenvisible-light components, and blue visible-light components and infraredlight with wavelengths including the wavelengths of excitation lightcomponents but not including the wavelengths of fluorescence can betransmitted simultaneously.

[0171] The camera head 4B is identical to the camera head 4A in FIG. 1except that the second CCD 26 alone is placed to handle lighttransmitted by the dichroic mirror 22. Reflected light is handled by thesame components as those in FIG. 1.

[0172] Output signals produced by the two CCDs 25 and 26 are input tothe processor 5A. The other components are identical to those in FIG. 1.

[0173] Next, the operation of this embodiment will be described.

[0174] Light radiated from the lamp 11 in the light source apparatus 3Bis supplied to the light guide connector 10 in the endoscope 2A by wayof the bandpass filter 12, illumination light diaphragm 13, RGB rotaryfilter 41, and condenser 14, and irradiated to the living tissue 17 byway of the light guide fiber 9 and illumination lens 16.

[0175] The RGB rotary filter 41 has, as shown in FIG. 12, the red,green, and blue filters 43R, 43G, and 43B arranged therein, andtransmits red, green, and blue light rays when driven to rotate 30 timesper second by means of the motor 42. The red, green, and blue filters43R, 43G, and 43B embedded in the RGB rotary filter 41 exhibit thespectroscopic characteristics of transmission shown in FIG. 13. Any ofred, green, and blur light rays is transmitted, and infrared lightcontaining excitation light components for exciting an antibody labeledby indocyanine green is transmitted at the same time.

[0176] Moreover, the bandpass filter 12 has the characteristic shown inFIG. 2. When the bandpass filter 12 and RGB rotary filter 41 are used incombination, one of red, green, and blue visible-light components andinfrared light with wavelengths including the wavelengths of excitationlight but not including the wavelengths of fluorescence are transmittedsimultaneously.

[0177] Reflected light and fluorescence stemming from the living tissue17 are input to the camera head 4B mounted on the eyepiece unit of theendoscope 2A through the image guide fiber 19. Light incident on thecamera head 4B has infrared light components and visible lightcomponents thereof separated therefrom by means of the dichroic mirror22 having the characteristic shown in FIG. 3.

[0178] The infrared light components reflected by the dichroic mirror 22are amplified by the image intensifier 24 after passed by the excitationlight cutoff filter 23 having the characteristic shown in FIG. 4, andthen detected by the first CCD 25.

[0179] The first CCD 25 is driven synchronously with the rotation of theRGB rotary filter by means of a CCD drive circuit that is not shown. Afluorescence image depicted by fluorescence emanating from an antibodylabeled by indocyanine green is produced at the rate of 30 frames persecond.

[0180] Visible light components transmitted by the dichroic mirror 22are input to the second CCD 26. The second CCD 26 is drivensynchronously with the rotation of the RGB rotary filter by means of theCCD drive circuit that is not shown. Red, green, and blue images areproduced successively at the rate of 90 frames per second. A signaloutput from the second CCD 26 is processed by the processor 5A, wherebythe signal components representing the red, green, and blue images aretimed. Consequently, a normal visible image is produced.

[0181] Signals produced by the two CCDs 25 and 26 are sent to thepre-processing circuit 31, A/D conversion circuit 32, video signalprocessing circuit 33, and D/A conversion circuit 34 in the processor5A, and then output to the monitor 6.

[0182] In this embodiment, a single lamp is used as a light source meansfor observation. Alternatively, two or more light sources, for example,a halogen lamp for normal light observation and a laser diode orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0183] Moreover, illumination light for use in exciting a fluorescentsubstance may be irradiated in vitro.

[0184] Moreover, the camera head 4B may not be employed. Thelight-receiving devices of the CCDs 25 and 26 may be incorporated in theprocessor 5A, and the endoscope 2A and processor 5A may be connectedusing an optical connector. The endoscope 2A may thus be designed to belightweight and compact.

[0185] For removing excitation light, instead of placing the excitationlight cutoff filter 23 on the face of the image intensifier 24, adichroic mirror characteristic of not reflecting excitation light may beused as the dichroic mirror 22.

[0186] Moreover, field-by-field processing may be substituted forframe-by-frame processing.

[0187] This embodiment has the advantages described below.

[0188] According to the embodiment, infrared fluorescence emanating froman antibody labeled by indocyanine green can be observed. Moreover,since a separating means for separating infrared fluorescence andvisible light is included, an infrared fluorescence image expressing thestate of an object attained at nearly the same time instant as the stateof an object depicted by normal visible light can be produced.

[0189] Next, the fourth embodiment of the present invention will bedescribed. An object of this embodiment is to provide a fluorescentendoscope system capable of producing a visible light image and aninfrared fluorescence image depicted by fluorescence emanating from anantibody labeled by indocyanine green, and capable of being realizedusing a compact imaging system.

[0190] The fourth embodiment is configured similarly to the firstembodiment. A difference will be described mainly. The same referencenumerals will be assigned to components having similar functions. Thedescription of the components will be omitted.

[0191] A fluorescent endoscope system 1D in accordance with the fourthembodiment shown in FIG. 14 is different from the fluorescent endoscopesystem 1B shown in FIG. 8 in points that an electronic endoscope 2Cadopts an excitation light cutoff filter 50 instead of the mosaic filter37 included in the electronic endoscope 2B, a processor 5B includes afilter control circuit 51 in addition to the components of the processor5A, and a light source apparatus 3C has an RGB rotary filter 41 to bedriven to rotate by a motor 42 placed on an optical path linking theillumination light diaphragm 13 and condenser 14 included in the lightsource apparatus 3A, and includes a spectrum restriction rotary filter52 to be driven to rotate by a motor 53 in place of the bandpass filter12.

[0192] The spectrum restriction rotary filter 52 has, as shown in FIG.15, a semicircular visible-light transmission filter 54 andinfrared-light transmission filter 55 placed as halves of a circle.

[0193] The visible-light transmission filter 54 and infrared-lighttransmission filter 55 exhibit the spectroscopic transmittances shown inFIG. 16, and transmit normal observation visible light and excitationinfrared light respectively.

[0194] Moreover, the excitation light cutoff filter 50 exhibits thespectroscopic characteristic of transmission shown in FIG. 17, andtransmits visible light components and fluorescence components withwavelengths in the infrared spectrum and cuts off excitation lightcomponents with wavelengths in the infrared spectrum.

[0195] The light source apparatus 3C has, similarly to the one describedin conjunction with FIG. 12, the RGB rotary filter 41. The RGB rotaryfilter 41 is driven to rotate by the motor 42. Moreover, the spectrumrestriction filter 52 for restricting the wavelengths of transmittedlight is placed on the optical path linking the lamp 11 and illuminationlight diaphragm 13, and driven by the motor 53.

[0196] Rotations of the motors 42 and 53 are controlled by a filtercontrol circuit 51. For example, when an operator presses an observationmode selection switch, which is not shown, to designate a normalobservation mode, the filter control circuit 51 gives control so thatthe motor 53 is rotated (and stopped) by a given magnitude (given angle)in order to keep the visible-light transmission filter 54 lying on theoptical path. Moreover, the rotating speed of the motor 42 is controlledso that the RGB rotary filter 41 can be rotated 30 times per second.

[0197] Moreover, when an operator presses the observation mode selectionswitch to designate a fluorescence observation mode, the filter controlcircuit 51 gives control so that the motor 53 is rotated (and stopped)by a given magnitude (given angle) in order to keep the infrared-lighttransmission filter 55 lying on the optical path. Moreover, the rotatingspeed of the motor 42 is controlled so that the RGB rotary filter 41 canbe rotated 30 times per second.

[0198] Furthermore, when an operator presses the observation modeselection switch to designate a fluorescence/normal light simultaneousobservation mode, the filter control circuit 51 controls the rotatingspeed of the motor 53 so that the spectrum restriction rotary filter 52can be rotated 90 times per second, and controls the rotating speed ofthe motor 42 so that the RGB rotary filter 41 can be rotated 30 timesper second synchronously with the rotation of the spectrum restrictionrotary filter.

[0199] The other components are identical to those in the fluorescentendoscope system 1B shown in FIG. 8.

[0200] Next, the operation of this embodiment will be described.

[0201] Light radiated from the lamp 11 in the light source apparatus 3Cis supplied to the light guide connector 10 in the electronic endoscope2C after passed by the spectrum restriction rotary filter 52,illumination light diaphragm 13, RGB rotary filter 41, and condenser 14,propagated over the light guide filter 9, and then irradiated to theliving tissue 17.

[0202] The visible-light transmission filter 54 and infrared-lighttransmission filter 55 of the spectrum restriction rotary filter 52exhibit the spectroscopic transmittances shown in FIG. 16, and transmitvisible light for normal observation and infrared light for excitationrespectively.

[0203] The RGB rotary filter 41 has, as shown in FIG. 12, red, green,and blue filters 43R, 43G, and 43B arranged therein. The filters 43R,43G, and 43B exhibit the spectroscopic characteristics of transmissionshown in FIG. 13. Any of red, green, and blue light rays is transmitted,and infrared light with wavelengths including the wavelengths ofexcitation light for exciting an antibody labeled by indocyanine greenis transmitted at the same time.

[0204] In normal light observation, the visible-light transmissionfilter 54 of the spectrum restriction rotary filter 52 is locked on theoptical path. As shown in the explanatory diagram of FIG. 18 concerningoperations for normal observation, the spectrum restriction rotaryfilter 52 transmits visible light. At this time, the RGB rotary filter41 is rotated 30 times per second in order to transmit red, green, andblue light rays. These light rays are irradiated successively to theliving tissue 17.

[0205] Light having the wavelengths of the red, green, and blue lightrays is received on the light-receiving plane of the CCD 39, andphotoelectrically converted. The CCD 39 then outputs a signalrepresenting an image formed with red, green, and blue color components.The signal is processed by the processor 5B. A normal endoscopic imagedepicted by visible light is displayed on the monitor 6.

[0206] In fluorescence observation, the infrared-light transmissionfilter 55 of the spectrum restriction rotary filter 52 is locked on theoptical path. As shown in the explanatory diagram of FIG. 19 concerningoperations for fluorescence observation, the spectrum restriction rotaryfilter 52 transmits infrared light.

[0207] At this time, the RGB rotary filter 41 is rotated 30 times persecond in order to transmit infrared light having the wavelengths ofexcitation light. The infrared light having the wavelengths ofexcitation light is irradiated to the living tissue 17.

[0208] The excitation light cutoff filter 50 exhibiting thespectroscopic characteristic of transmission shown in FIG. 17, that is,capable of transmitting visible light components and fluorescencecomponents with wavelengths in the infrared spectrum and cutting offexcitation light components with wavelengths in the infrared spectrum islocated in front of the light-receiving plane of the CCD 39.

[0209] Owing to the excitation light cutoff filter 50, excitation lightis cut off. Fluorescence emanating from a fluorescent substance(antibody labeled by indocyanine green) is received andphotoelectrically converted, whereby a signal representing afluorescence image is output.

[0210] The fluorescence image is displayed on the monitor 6.

[0211] Moreover, for observing a fluorescence image and normal lightimage simultaneously, the spectrum restriction rotary filter 52 isrotated 90 times per second. As shown in the explanatory diagram of FIG.20 concerning operations for fluorescence/normal light simultaneousobservation, the spectrum restriction rotary filter 52 transmits visiblelight and infrared light. The rotary filter 41 is rotated 30 times persecond in order to successively transmit red light, excitation light,green light, excitation light, blue light, and excitation light. Theselight rays are irradiated to the living tissue 17.

[0212] Thus, the filter control circuit 51 gives control so that the RGBrotary filter 41 and spectrum restriction rotary filter 52 are rotatedmutually synchronously.

[0213] Reflected light and fluorescence stemming from the living tissue17 are passed by the excitation light cutoff filter 50 and detected bythe CCD 39. The CCD 39 receives visible light of red, green, and blue orinfrared fluorescence according to the positions of the RGB rotaryfilter 42 and spectrum restriction rotary filter 52.

[0214] The CCD 39 is driven synchronously with the rotations of thefilters 41 and 52 by means of a CCD drive circuit that is not shown, andoutputs an image signal representing 180 frames per second responsivelyto the rotation of the spectrum restriction rotary filter 52.

[0215] The output signal of the CCD 39 is processed by the processor 5B,whereby a fluorescence image and normal light image are displayed on themonitor 6.

[0216] As mentioned above, in this embodiment, a signal produced by theCCD 39 is sent to the pre-processing circuit 31, A/D conversion circuit32, video signal processing circuit 33, and D/A conversion circuit 34 din the processor 5B, and then output to the monitor 6. Thepre-processing circuit 31 and video signal processing circuit 33 carryout processing associated with normal light observation, fluorescenceobservation, or normal light/fluorescence simultaneous observationaccording to a signal sent from the filter control circuit 51.

[0217] According to this embodiment, infrared fluorescence emanatingfrom an antibody labeled by indocyanine green can be observed. Moreover,since one imaging device is used to observe both normal light andfluorescence, the imaging system becomes compact.

[0218] In this embodiment, a single lamp is used as a light source meansfor observation. Alternatively, two or more light sources, for example,a halogen lamp for normal light observation and a laser diode orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0219] Moreover, illumination light for use in exciting a fluorescentsubstance may be irradiated in vitro.

[0220] Next, the fifth embodiment of the present invention will bedescribed. An object of this embodiment is to make it possible to viewboth a fluorescence image and normal light image simultaneously and torecognize the intensity of fluorescence more accurately.

[0221] In a fluorescent method of diagnosis in which a fluorescentsubstance is administered to a body for endoscopic diagnosis,fluorescence of what brightness level is being emitted must berecognized quickly and accurately. However, using a conventionalconfiguration, it is hard to accurately grasp the positionalrelationship between a fluorescence image and normal light image or theintensity of fluorescence.

[0222] For example, when a fluorescence image alone is viewed, even ifthe image has a bright area, it is hard to judge whether the area isbright because a large amount of light is emanating from a lamp, thearea is bright because an object is located nearby, the area is brightbecause the amplification factor of a video signal is high, or the areais bright because a fluorescent substance is accumulated.

[0223] Moreover, it has been impossible in the past that a normal lightimage and fluorescence image are synthesized and displayed withinformation of the intensity of fluorescence held intact.

[0224] An example of a configuration for solving the above problem willbe described below.

[0225] As shown in FIG. 21, a fluorescent endoscope system 1E inaccordance with the fifth embodiment comprises an endoscope 2D to beinserted into a body cavity for observing or diagnosing the inside ofthe body cavity, a light source apparatus 3D for emitting light forobservation or for excitation, a camera head 4A mounted on the endoscope2D and having an imaging device therein, a processor SC for processing asignal produced by the imaging means, and a monitor 6 for displayingimages.

[0226] In this embodiment, an electronic endoscope having an imagingmeans is realized with a camera-mounted endoscope constructed bymounting the freely detachable camera head 4 on the eyepiece unit of theoptical endoscope 2D.

[0227] The endoscope 2D has the elongated flexible insertional part 8 tobe inserted into a body cavity. The light guide fiber 9 over whichillumination light is propagated and the image guide fiber 19 over whichlight stemming from a living tissue is propagated are run through theinsertional part 8. A light guide connector 10 located at an incidentend of the light guide fiber 9 placed near an operator's hand is freelydetachably attached to the light source apparatus 3D. The camera head 4Dis freely detachably attached to the back end of the image guide fiber19.

[0228] The light source apparatus 3D includes a lamp 61 for radiatinglight containing visible light, an infrared light cutoff filter 61located on the path of illumination light radiated from the lamp 61 forrestricting the wavelengths of transmitted light, an infrared laser 63for radiating laser light with wavelengths in the infrared spectrum, amirror 64 for transmitting light with wavelengths in the visiblespectrum and reflecting light with wavelengths in the infrared spectrum,an illumination light diaphragm 65 for restricting an amount of light, acondenser for concentrating light, and a light emission control circuit67 for controlling amounts of light emitted from the lamp 61 andinfrared laser 63.

[0229] The camera head 4A includes the image formation lens 21, thedichroic mirror 22 for separating infrared light components and visiblelight components, the excitation light cutoff filter 23 for removingexcitation light components from the separated infrared light, the imageintensifier 24 for amplifying infrared light, the first CCD 25 forreceiving light amplified by the image intensifier 24, the dichroicprism 29 for separating red, green, and blue light rays from visiblelight components, the second CCD 26 for receiving red light, the thirdCCD 29 for receiving green light, and the fourth CCD 27 for receivingblue light.

[0230] The processor 5C includes a pre-processing circuit 71 foramplifying image signals produced by the first to fourth CCDs 25 to 28,and carrying out pre-processing such as color balance adjustment, an A/Dconversion circuit 72, a video signal processing circuit 73 for carryingout processing such as marker production and image synthesis, an D/Aconversion circuit 74, and a screen display setting unit 75 for settingan image display mode.

[0231] The pre-processing circuit 71 includes, as shown in FIG. 22, anautomatic light adjustment circuit 81 for producing a light adjustmentsignal, a color balance correction circuit 82 for adjusting a colorbalance, and an automatic gain control (AGC) circuit 83 forautomatically controlling a gain.

[0232] The video signal processing circuit 73 includes, as shown in FIG.23, a multiplexer 86 for selecting any of color signals, a divisioncircuit 87 for carrying out division for infrared light components (IR)and red light components (R), a marker production circuit 88 forproducing markers on the basis of an output of the division circuit 87,and an image synthesis circuit 89 for synthesizing an output of themultiplexer 86 with an output of the marker production circuit 88.

[0233] Next, the operations of the fluorescent endoscope system 1Ehaving the foregoing components will be described.

[0234] Similarly to the first embodiment, a fluorescent substance thatis an antibody labeled by indocyanine green is administered to a livingtissue in advance and accumulated in a lesion. Light with wavelengths of770 to 780 nm is irradiated as excitation light to the inside of a bodyusing the light source apparatus 3D. Light with wavelengths of 810 to820 nm is detected as fluorescence. Thus, presence or absence of alesion can be recognized.

[0235] The lamp 61 in the light source apparatus 3D is a xenon lamp andradiates light with wavelengths including the wavelengths in the visiblespectrum. Light radiated from the lamp 61 is passed by the infraredlight cutoff filter 62 and falls on the mirror 64. The infrared lightcutoff filter 62 is a filter for transmitting red, green, and bluevisible light rays and removing light with wavelengths in the infraredspectrum. Light with wavelengths in the visible spectrum passed by theinfrared light cutoff filter 62 is transmitted by the mirror 64. Anamount of the light is then adjusted by the illumination light diaphragm65.

[0236] The infrared laser 63 is a semiconductor laser and radiates laserlight with wavelengths of about 780 nm which excites an antibody labeledby indocyanine green. Laser light radiated from the infrared laser 63 isdiffused by an optical system that is not shown, and then reflected fromthe mirror 64. The amount of the laser light is then adjusted by theillumination light diaphragm 65.

[0237] The illumination light diaphragm 65 has the ability to adjustboth an amount of light radiated from the lamp 61 and an amount of lightradiated from the infrared laser 63. At this time, the amounts of lightradiated from the lamp 61 and infrared laser 63 are controlled by thelight emission control circuit 67. Light passed by the illuminationlight diaphragm 65 is concentrated on the light guide fiber 9 in theendoscope 2D by means of the condenser 66, and irradiated to a livingtissue from the distal endoscope part through the light guide fiber 9.

[0238] Light radiated from the light source apparatus 3D is absorbed orreflected by the living tissue. Fluorescence is emitted from an antibodylabeled by indocyanine green administered in advance and accumulated ina lesion because the antibody is excited by irradiated excitation light.

[0239] With reflected light and fluorescence stemming from the livingtissue, images are formed on the distal end of the image guide fiber 19,transmitted to the back end of the image guide fiber 19, and then inputto the camera head 4A mounted on the endoscope 2D via the imageformation lens 21.

[0240] Light input to the camera head 4A has infrared light componentsand visible light components separated therefrom by means of thedichroic mirror 22. The dichroic mirror 22 exhibits the spectroscopiccharacteristic of transmission shown in FIG. 3. The visible lightcomponents are transmitted and the other light components are reflected.

[0241] The infrared light components reflected by the dichroic mirror 22are passed by the excitation light cutoff filter 23, amplified by theimage intensifier 24, and then detected by the first CCD 25. Theexcitation light cutoff filter 23 exhibits the spectroscopiccharacteristic of transmission shown in FIG. 4. Excitation lightcomponents emanating from an antibody labeled by indocyanine green areremoved and fluorescence components are transmitted.

[0242] The image intensifier 24 is sensitive to the wavelengths of about350 nm to 910 nm and capable of detecting fluorescence emanating from anantibody labeled by indocyanine green. Thus, the first CCD 25 detectsfluorescence components emanating from the antibody labeled byindocyanine green.

[0243] The visible light components passed by the dichroic mirror 22 areinput to a three-plate camera composed of the dichroic prism 29 and thethree CCDs 26, 27, and 28. The dichroic prism 29 separates red, green,and blue light components from incident light, and routes the lightcomponents to the second CCD 26, third CCD 27, and fourth CCD 28. Thus,the second to fourth CCDs 26 to 28 detect normal visible lightcomponents (normal light images).

[0244] The first to fourth CCDs 25 to 28 are driven mutuallysynchronously by a CCD drive circuit that is not shown. Each of the CCDsproduce 30 frame images per second.

[0245] The infrared, red, green, and blue light signals (IR, R, G, andB) output from the CCDs 25 to 28 are input to the pre-processing circuit71 in the processor 5C. The signals sent from the CCDs to thepre-processing circuit 71 are amplified by a preamplifier that is notshown, and input to the automatic light adjustment circuit 81 shown inFIG. 22. A control signal (light adjustment signal) for use incontrolling the illumination light diaphragm 65 in the light sourceapparatus 3D is then produced.

[0246] The automatic light adjustment circuit 81 uses signals outputfrom the second to fourth CCDs 26 to 28 designed for normal lightobservation to produce a light adjustment signal for use in specifying agiven amount of illumination light on the basis of an amount ofreflected light of light with wavelengths in the visible spectrumstemming from a living tissue. The light adjustment signal output fromthe automatic light adjustment circuit 81 is input to the illuminationlight diaphragm 65 in the light source apparatus 3D. Based on the lightadjustment signal, an amount of light passed by the illumination lightdiaphragm 65 is controlled. Owing to this configuration, an amount oflight emitted from the infrared laser 63 for exciting a fluorescentsubstance and irradiated to a living tissue is controlled properly onthe basis of the brightness of a normal light image. It will thereforenot take place that the brightness of a fluorescence image is judgedincorrectly because an amount of light for exciting a fluorescentsubstance is too large or small.

[0247] Moreover, signals output from the CCDs and input to thepreprocessing circuit 71 are also input to the color balance correctioncircuit 82. The color balance correction circuit 82 adjusts colorbalance indicated by the signals in relation to the levels of signalsproduced by imaging a color balance adjuster, which is not shown,serving as a color reference.

[0248] The color balance adjuster exhibits a nearly constant reflectancerelative to light with wavelengths in the visible spectrum. A substancethat emits, like an antibody labeled by indocyanine green, fluorescencewith wavelengths of about 810 to 820 nm when excited by excitation lightwith wavelengths of about 770 to 780 nm is applied to the color balanceadjuster. When the color balance adjuster is used to adjust colorbalance, the color balance of red, green, blue as well as infrared isadjusted by the color balance correction circuit 82. Consequently, atone defect resulting from a difference in performance of a lamp in alight source apparatus or an infrared laser, a difference inspectroscopic transmittance of a light guide fiber or image guide fiberin an endoscope, or a difference in sensitivity of a CCD can becorrected.

[0249] Signals output from the CCDs and passed by the color balancecorrection circuit 82 are input to the AGC circuit 83 that controls thegains of the signals. The signals output from the second to fourth CCDs26 to 28 designed for normal light observation are input to anamplification factor calculation circuit 84 in the AGC circuit 83. Anamplification factor in the amplification circuit 85 is determined onthe basis of an amount of reflected light of normal light withwavelengths in the visible spectrum stemming from a living tissue. Thedetermined amplification factor is sent to the amplification circuit 85.The signals output from the CCDs and input to the AGC circuit 83 areamplified according to the amplification factor.

[0250] Owing to the above configuration, a signal representing afluorescence image is amplified properly on the basis of the brightnessof a normal light image. It will therefore not take place that thebrightness of a fluorescence image is Judged incorrectly because theamplification factor of the signal representing the fluorescence imageis too high or low.

[0251] Signals output from the AGC circuit 83 in the pre-processingcircuit 71 are input to the A/D conversion circuit 72, and convertedinto digital signals (IR′, R′, G′, and B′). Thereafter, the signals aresent to the video signal processing circuit 73, and input to themultiplexer 86 shown in FIG. 23.

[0252] According to a setting signal output from the screen displaysetting unit 75, the multiplexer 86 selects any of input terminals 6R,6G, and 6B of the monitor 6 to which any of the signals (IR′, R′, G′,and B′) sent from the CCDs 25 to 28 is allocated.

[0253] Among the signals input to the video signal processing circuit73, the signals R′ and IR′ are input to the division circuit 87. Aquotient IR″ of the signal level IR′ by the signal level R′ iscalculated for each pixel in an image. Consequently, a fluorescenceimage is normalized by a red light image. The color of mucosa inside ahuman body is dominated by an amount of hemoglobin that is a pigment. Asshown in FIG. 24, hemoglobin is characteristic of a large absorbance oflight with wavelengths of 600 nm or shorter.

[0254] In this embodiment, normalization is carried out using an imagedepicted by red light with wavelengths of 600 nm or longer as areference image. A change in apparent intensity of fluorescencedependent on the positional relationship between a region to be observedand a distal end of an endoscope can be canceled with a little influenceof an amount of hemoglobin. The signal IR″ representing a normalizedfluorescence image can therefore be used as a signal accuratelyindicating the intensity of actual fluorescence or the degree ofaccumulation of an antibody labeled by indocyanine green.

[0255] The signal IR″ output from the division circuit 87 is input tothe marker production circuit 88. The marker production circuit 88produces markers marking high signal levels of the signal IR″ and alsoproduces an image graphically indicating the high levels of the signalIR″ marked by the markers.

[0256] An output of the multiplexer 86 and an output of the markerproduction circuit 88 are input to the image synthesis circuit 89,whereby image synthesis is carried out. The image synthesis circuit 89synthesizes (superimposes) image signals representing the markers andgraph produced by the marker production circuit 88 with an image signaloutput from the multiplexer 86, and outputs a synthetic image.

[0257] A synthetic image signal output from the image synthesis circuit89 in the video signal processing circuit 73 is input to the D/Aconversion circuit 74, converted into an analog signal, and input to themonitor 6. An image is then displayed. On the monitor 6, a normal lightimage and fluorescence image can be viewed according to settingdetermined by the screen display setting unit 75.

[0258] A user manipulates a switch on an operation unit of the endoscopewhich is not shown, and chooses any of four observation modes of (1)normal light sole observation, (2) fluorescence sole observation, (3)normal light/fluorescence synthesis observation, and (4) normallight/fluorescence marker observation. The screen display setting unit75 sets a screen display on the basis of a screen display setting signalsent from the operation unit of the endoscope, and sends a settingsignal to the multiplexer 86 and image synthesis circuit 89 in the videosignal processing unit 73. At this time, a light emission control signalis sent from the screen display setting unit 75 to the light emissioncontrol circuit 67 in the light source apparatus 3D. Thus, lightemission is controlled according to the setting of a screen display.

[0259] When normal light sole observation is designated, the lamp 61alone glows under the control of the light emission control circuit 67on the basis of a light emission control signal sent from the screendisplay setting unit 75. The infrared laser 63 stops emitting light.With a setting signal sent from the screen display setting unit 75, themultiplexer 86 and image synthesis circuit 89 in the video signalprocessing unit 73 are controlled. The multiplexer 86 selects an outputdestination so that a signal R′ representing a red reflected light imagewill be applied to an input terminal 6R of the monitor, a signal G′representing a green reflected light image will be applied to an inputterminal 6G thereof, and a signal B′ representing a blue reflected lightimage will be applied to an input terminal 6B thereof. The imagesynthesis circuit 89 does not synthesize a marker image with a normallight image but outputs the signal representing the normal light image.As a result, the normal light image alone is displayed in colors on themonitor 6.

[0260] When fluorescence sole observation is designated, both the lamp61 and infrared laser 63 glow under the control of the light emissioncontrol circuit 67 on the basis of a light emission control signal sentfrom the screen display setting unit 75. At this time, according to asetting signal sent from the screen display setting unit 75, themultiplexer 86 selects an output destination so that a signal IR′representing a fluorescence image will be applied to all the inputterminals 6R, 6G, and 6B of the monitor. The image synthesis circuit 89does not synthesize a marker image with the fluorescence image butoutputs the signal representing the fluorescence image. As a result, thefluorescence image alone is displayed monochromatically on the monitor6.

[0261] When normal light/fluorescence synthesis observation isdesignated, both the lamp 61 and infrared laser 63 glow under thecontrol of the light emission control circuit 67 on the basis of a lightemission control signal sent from the screen display setting unit 75. Inthis case, the lamp 61 is allowed to glow in order to enable theautomatic light adjustment circuit 81 to adjust light and enable theamplification factor calculation circuit 84 to determine anamplification factor for a fluorescence image.

[0262] At this time, the multiplexer 86 selects an output destinationaccording to a setting signal sent from the screen display setting unit75 so that a signal G′ representing a green reflected light image willbe applied to the red input terminal 6R of the monitor 6 and blue inputterminal 6B thereof, and a signal IR′ representing a fluorescence imagewill be applied to the green input terminal 6G of the monitor 6.

[0263] The image synthesis circuit 89 does not synthesize a marker imagewith the reflected light and fluorescence images but outputs the signalsrepresenting the images. As a result, the reflected light image (green)and fluorescence image are displayed in different colors on the monitor6. FIG. 23 shows the multiplexer 86 in the foregoing selected state.

[0264] An antibody labeled by indocyanine green is not accumulated in anormal mucosa inside a body. Images depicted by reflected lightcomponents that are green visible light are displayed in red and blue onthe monitor. Green on the monitor gets very dark because of almost nofluorescence components. Consequently, the normal mucosa appears inpurple on the monitor 6. Moreover, infrared fluorescence stems from aregion in which the antibody labeled by indocyanine green is apt to beaccumulated, such as, a carcinoma. The lesion is therefore displayed ingreenish color on the monitor 6.

[0265] As mentioned above, in the normal light/fluorescence synthesisobservation mode, a normal region can be distinguished from a lesion dueto a difference in color. This is helpful in diagnosis. Moreover, sincea green reflected light image well-reflects the structure-of the mucosa,the positional relationship between a fluorescence image and normallight image can be grasped easily.

[0266] When normal light/fluorescence marker observation is designated,both the lamp 61 and infrared laser 63 glow under the control of thelight emission control circuit 67. At this time, the multiplexer 86selects an output designation according to a setting signal sent fromthe screen display setting unit 75 so that a signal R′ representing ared reflected light image will be applied to the red input terminal 6Rof the monitor 6, a signal G′ representing a green reflected light imagewill be applied to the green input terminal 6G thereof, and a signal B′representing a blue reflected light image will be applied to the blueinput terminal 6B thereof.

[0267] The image synthesis circuit 89 synthesizes a marker image with anormal light image and outputs a resultant synthetic image. As a result,the normal light image is displayed on the monitor 6 with markersindicating high intensities of fluorescence superimposed on the normallight image. The levels (intensities of fluorescence) of the normalizedfluorescence signal IR″ associated with the markers are displayedgraphically in a left lower area on the monitor screen. The possibilitythat a region indicated with a marker may be a lesion can be recognizedat sight.

[0268]FIG. 25 shows an example of the above screen display on themonitor 6. In normal light/fluorescence marker observation, a normallight image 91 depicted by normal light is displayed in an octagonalarea on the right hand of the screen. Regions fluorescing at highintensities are indicated with markers A, B, and C within the normallight image 91. Moreover, a graph is displayed in the left lower cornerof the screen. The lengths of bars of the graph associated with themarkers A, B, and C indicate the intensities IR″ of fluorescence. If adisplay image has no portion thereof represented by the signal IR″ witha given level or higher, no marker is displayed.

[0269] In this embodiment, visible light is also irradiated asillumination light for observation from a light source. Alternatively,red, green, blue, and infrared (excitation) light rays may be irradiatedcolor-sequentially from the light source, and a CCD may be placed in thedistal end of the insertional part of an endoscope. The signalprocessing method of this embodiment can still be adapted to thisconfiguration.

[0270] Moreover, adjustment of amounts of light emanating from the lamp61 and infrared laser 63 in the light source apparatus is not limited toadjustment using the illumination light diaphragm 65. Alternatively, anamount of emitted light may be controlled by controlling a current orvoltage. Moreover, a light-emitting diode may be placed as a lightsource means at the distal end of the insertional part of an endoscope.Moreover, since illumination light for exciting a fluorescent substanceis transmitted efficiently by a living tissue, the light may beirradiated in vitro.

[0271] Moreover, the camera head 4A may not be used as an imaging means.Alternatively, a light-receiving device such as a CCD may beincorporated in the processor 5C. The endoscope 2D and processor 5C maybe connected using an optical connector. In this case, the endoscope canbe designed to be lightweight and compact. Moreover, a single-platecamera having a mosaic filter on the face of the CCD may be substitutedfor the three-plate camera, and used to detect normal light. Thisresults in reduced cost.

[0272] Moreover, a method of removing excitation light is not limited tothe method in which the excitation light cutoff filter 23 is placed onthe face of the image intensifier 24. Alternatively, a dichroic mirrorcharacteristic of not reflecting excitation light components may be usedas the dichroic mirror 22.

[0273] Normalization of a fluorescence image is not limited tonormalization relative to a red light image. Alternatively, an imagedepicted by infrared fluorescence components may be used for thenormalization.

[0274] Moreover, in fluorescence observation, instead of displaying afluorescence image (IR′) as it is, a normalized fluorescence image (IR″)may be displayed on the monitor 6. Moreover, colors displayed on themonitor 6 are not limited to those based on red, green, and blue but maybe those based on cyan, magenta, and yellow.

[0275] Moreover, color components of reflected light to be displayed onthe monitor when normal light/fluorescence synthesis observation isdesignated are not limited to green light but may be red light.Moreover, green light and red light may be input as different colorsignals to the monitor. When normal light/fluorescence simultaneousobservation is designated, an input terminal through which afluorescence image signal (IR″) is input is not limited to the greeninput terminal 6G of the monitor 6. Alternatively, the fluorescenceimage signal may be allocated to two or more input terminals among thered input terminal 6R, blue input terminal 6B, and green input terminal6G.

[0276] This embodiment has the advantage described below.

[0277] According to this embodiment, both a fluorescence image andnormal light image can be viewed simultaneously, and the intensity offluorescence can be discerned accurately.

[0278] Next, the sixth embodiment of the present invention will bedescribed. When a fluorescence image depicted by fluorescence emanatingfrom an antibody labeled by indocyanine green (ICG) is viewed on amonitor, a region in which the fluorescent substance is not accumulatedis visualized completely dark. An object of this embodiment is thereforeto provide a fluorescent endoscope system making it possible torecognize the orientation (direction) of an object shown in an imageeven during fluorescence observation and making it easy to manipulate anendoscope or conduct an endoscopic treatment.

[0279] A fluorescent endoscope system 1F of the sixth embodiment of thepresent invention shown in FIG. 26 is different from the fluorescentendoscope system 1E of the fifth embodiment shown in FIG. 21 in pointsthat a camera head 4C has a second dichroic mirror 92 and fifth CCD 93in addition to the components of the camera head 4A and that a videosignal processing circuit 73A having the configuration shown in FIG. 27is substituted for the video signal processing circuit 73 in theprocessor 5C.

[0280] The second dichroic mirror 92 is placed on an optical pathlinking the dichroic mirror 22 for reflecting light with wavelengths of700 nm or longer and the excitation light cutoff filter 23. As shown inFIG. 26, the dichroic mirror 92 is characteristic of reflecting lightwith wavelengths of less than 800 nm and transmitting light withwavelengths of 800 nm or longer.

[0281] The video signal processing circuit 73A shown in FIG. 27 iscomposed of five frame memories, in particular, red, green, and bluememories 94 a, 94 b, and 94 c and two infrared memories 94 d and 94 e,and a multiplexer 95 for selecting an output destination for each of theframe memories. Selection performed by the multiplexer 95 is controlledby the screen display setting unit 75. FIG. 27 shows a selected state ofthe multiplexer 95 in which a fluorescence synthetic observation mode tobe described later is selected.

[0282] Next, the operation of the sixth embodiment will be described byreferring mainly to a difference from the fifth embodiment. Visiblelight and infrared excitation light emitted from the light sourceapparatus 3D are irradiated to a living tissue through the endoscope 2D.Reflected light and fluorescence stemming from the living tissue fall onthe camera head 4C through the endoscope 2D.

[0283] Light incident on the camera head 4C has infrared lightcomponents and visible light components thereof separated therefrom bymeans of the dichroic mirror 22. The dichroic mirror 22 exhibits thecharacteristic shown in FIG. 3. The infrared light components reflectedfrom the dichroic mirror 22 fall on the second dichroic mirror 92.

[0284] The second dichroic mirror 92 reflects, as seen from thecharacteristic curve shown in FIG. 28, excitation light components andtransmits fluorescence components. The fluorescence componentstransmitted by the second dichroic mirror 92 have excitation lightcomponents, which cannot be removed perfectly by the second dichroicmirror 92, removed by the excitation light cutoff filter 23, areamplified by the image intensifier 24, and then detected by the firstCCD 25. The excitation light cutoff filter 23 exhibits the spectroscopiccharacteristic of transmission shown in FIG. 4.

[0285] Moreover, light with wavelengths of 700 to 800 nm that isreflected light components of excitation light is detected by the fifthCCD 93. On the other hand, visible light components transmitted by thedichroic mirror 22 are, like the ones in the fifth embodiment, detectedby the second, third, and fourth CCDs 26, 27, and 28.

[0286] Output signals of the CCDs 25, 26 to 28, and 93 (R, G, B, IR1,and IR2) are input to the pre-processing circuit 71 in the processor 5C.Herein, the signal R is an image signal representing red light, thesignal G is an image signal representing green light, the signal B is animage signal representing blue light, the signal IR1 is an image signalrepresenting infrared fluorescence, and the signal IR2 is an imagesignal representing reflected light of infrared excitation light.

[0287] The pre-processing circuit 71 carries out signal processing suchas amplification of an image signal. A signal passed by thepre-processing circuit 71 is input to the A/D conversion circuit 72,converted into a digital signal, and then input to the video signalprocessing circuit 73A.

[0288] Signals output from the A/D conversion circuit 62 are temporarilystored in the frame memories, that is, the red, green, and blue memories94 a to 94 c and the infrared memories 94 d and 94 e, and read accordingto the reading timing suitable to the format of a display on the monitor6. According to an output signal of the screen display setting unit 75,the multiplexer 95 determines which of the signals (R′, G′, B′, IR1′,and IR2′) that are output from the CCDs 25, 26 to 28, and 93 should beallocated to which of the red, green, and blue input terminals of themonitor 6 for display on the monitor 6.

[0289] A signal output from the multiplexer 95 is input to the D/Aconversion circuit 74, converted into an analog signal, and input to themonitor 6. On the monitor, according to the setting defined by thescreen display setting unit 75, a normal light image and fluorescenceimage are displayed. A user can view the normal light image andfluorescence image.

[0290] A screen display setting signal issued from a switch on anoperation unit of the endoscope which is not shown is input to thescreen display setting unit 75. A user can choose any of three modes of(1) normal light sole observation, (2) fluorescence syntheticobservation, and (3) normal light/fluorescence dual-screen observation.

[0291] When normal light sole observation is designated, a lightemission control signal is sent from the screen display setting unit 75to the light emission control circuit 67. The lamp. 61 alone glows andthe infrared laser 63 is turned off.

[0292] Moreover, a control signal is sent to the multiplexer 95 in thevideo signal processing circuit 73A. The multiplexer 95 selects anoutput destination so that a signal R′ will be applied to the red inputterminal 6R of the monitor 6, a signal G′ will be applied to the greeninput terminal 6G thereof, and a signal B′ will be applied to the blueinput terminal 6B thereof. Consequently, a normal light image isdisplayed at a proper position on the monitor 6.

[0293] When fluorescence synthesis observation is designated, a lightemission control signal is sent from the screen display setting unit 75to the light emission control circuit 67. Both the lamp 61 and infraredlaser 63 glow. At this time, the multiplexer 95 selects an outputdestination according to a setting signal sent from the screen displaysetting unit 75 so that a signal (IR2′) representing an image depictedby reflected light of excitation light will be applied to the red inputterminal 6R and blue input terminal 6B of the monitor 6 and a signal(IR′) representing a fluorescence image will be applied to the greeninput terminal 6G of the monitor 6. On the monitor 6, the image depictedby reflected light of excitation light and the fluorescence image aredisplayed in different colors at the same position.

[0294] For example, as shown in FIG. 29, displayed on the monitor is afluorescence synthetic image 6 d in which a contour or the like of anobject depicted by reflected light components of infrared excitationlight is expressed in purple, and a lesion depicted by fluorescencecomponents is expressed in green.

[0295] An antibody labeled by ICG is not accumulated in a normal mucosain a living body. Reflected light components of infrared excitationlight are therefore output as red and blue light components to themonitor 6. An image depicted by fluorescence components or green lightcomponents and displayed on the monitor 6 gets very dark. The normalmucosa is therefore expressed in purple on the monitor 6.

[0296] By contrast, a region in which the antibody labeled by ICG is aptto be accumulated, such as, a carcinoma fluoresces in the infraredspectrum. Green light components to be output to the monitor 6 get moreintense. Since excitation light components are absorbed by the antibodylabeled by ICG, reflected light components (red and blue lightcomponents on the monitor 6) of the excitation light get weaker.Consequently, the lesion is expressed in bright green on the monitor 6.

[0297] As mentioned above, a normal region and lesion are displayed indifferent tones. The lesion can therefore be detected easily due to adifference in color. Moreover, the endoscope 2D can be manipulated whilereflected light of excitation light is referenced. When the endoscope 2Dis manipulated, the orientation of the endoscope can be recognizedeasily. Even when forceps are used for biopsy, the endoscope can bemanipulated reliably. Thus, maneuverability can be improved.

[0298] When normal light/fluorescence dual-screen observation isdesignated, a light emission control signal is sent from the screendisplay setting unit 75 to the light emission control circuit 67. Boththe lamp 61 and infrared laser 63 glow. In the video signal processingcircuit 73A, the memories and multiplexer 95 are controlled by a controlcircuit that is not shown so that the same image as the one displayed innormal light sole observation can be displayed on the right half of themonitor 6 and the same image as the one displayed in fluorescencesynthetic observation can be displayed on the left half of the monitor6. FIG. 30 shows an example of images displayed on the monitor 6 in thismode.

[0299] In the example of a display shown in FIG. 30, both a normal lightimage 6 e and fluorescence image (more particularly, a fluorescencesynthetic image) 6 d are displayed.

[0300] In normal light/fluorescence dual-screen observation, the normallight image 6 e and fluorescence image 6 d can be viewed on the samemonitor 6 without the necessity of switching the images. Diversediagnoses can be carried out simultaneously, for example, while atumorous lesion is observed in the fluorescence image 6 d, the curedstate of ulcer can be assessed by checking the tone of the normal lightimage 6 e or the running state of vessels.

[0301] The sizes of the normal light image 6 e and fluorescence image 6d to be displayed in normal light/fluorescence dual-screen observationare not limited to the same size adopted in this embodiment.Alternatively, the fluorescence image 6 d may be displayed in a smallersize as a chile screen, the normal light image 6 e may be displayed in asmaller size as a child screen, or the images may be able to beswitched.

[0302] When fluorescence synthetic observation is designated, a signalrepresenting a fluorescent image (IR1′) is input to the monitor 6. Theinput terminal of the monitor 6 through which the signal is input is notlimited to the green input terminal 6G of the monitor 6 but may be thered input terminal 6R or blue input terminal 6B thereof. Alternatively,the signal may be allocated to two or more of the red, green, and blueinput terminals so that the signal can be input through two or moreinput terminals.

[0303] According to this embodiment, a fluorescence image and an imagedepicted by reflected light of excitation light can be displayed whileone of the images is superposed on the other. The orientation of anendoscope can therefore be recognized clearly. When the endoscope ismanipulated in order to carry out an endoscopic treatment while thefluorescence image is viewed, safety can be guaranteed.

[0304] Moreover, when a fluorescence image and an image depicted byreflected light of excitation light are displayed while one of theimages is superposed on the other, the images are displayed in differentcolors. A lesion and the contour or structure of an object can beidentified and easily discerned simultaneously. Diagnosis can thereforebe achieved properly, and an endoscopic treatment can be carried outproperly.

[0305] Next, the seventh embodiment of the present invention will bedescribed. In general, fluorescence observed after irradiation ofexcitation light is feeble and much darker than reflected light observedafter irradiation of normal light. According to a prior art, therefore,it is hard to produce both a fluorescence image and normal light imagewith proper brightness.

[0306] Accordingly, an object of this embodiment is to provide afluorescent endoscope system making it possible to observe an objectbrightly during fluorescence observation and observe the object with alarge depth of field during normal light observation.

[0307] A fluorescent endoscope system 101A in accordance with theseventh embodiment of the present invention shown in FIG. 31 comprisesan electronic endoscope 102A to be inserted into a body cavity forobservation, a light source apparatus 103A for emitting light for normalobservation and light for excitation, a processor 104A for carrying outsignal processing, a monitor 105 for displaying an image depicted bynormal light and an image depicted by fluorescence, and a laser lightsource 106 for emitting laser light used for a treatment.

[0308] The electronic endoscope 102A has an elongated insertional part107 to be inserted into a body cavity. An imaging means is incorporatedin a distal part 117 of the insertional part 107. A light guide fiber108 over which illumination light used for normal observation andexcitation light are propagated is run through the insertional part 107.An incident end of the light guide fiber 108 to be placed near anoperator's hand can be freely detachably attached to the light sourceapparatus 103A.

[0309] The light source apparatus 103A includes a lamp 110 for radiatinglight with wavelengths in the infrared spectrum and visible spectrum, arotary filter 111 located on the path of illumination light emanatingfrom the lamp 110 for restricting a spectrum, an illumination lightdiaphragm 112 for restricting an amount of light emanating from the lamp110, an RGB rotary filter 113, and a condenser 114 for concentratinglight.

[0310] The spectrum restriction filter 111 and RGB rotary filter 113 aredriven to rotate by motors 115 and 116 respectively.

[0311] The spectrum restriction filter 111 has, as shown in FIG. 32, avisible light transmission filter 111 a and an infrared lighttransmission filter 111 b. FIG. 33 shows the characteristic of thevisible light transmission filter 111 a concerning transmission and thecharacteristic of the infrared light transmission filter 111 bconcerning transmission.

[0312] Only light components with wavelengths in the visible spectrum orinfrared spectrum are extracted from light emanating from the lamp 110by means of the visible light transmission filter 111 a or infraredlight transmission filter 111 b. The amount of extracted light iscontrolled by the illumination light diaphragm 112. The resultant lightthen falls on the RGB rotary filter 113.

[0313] The RGB rotary filter 113 is, as shown in FIG. 34, composed ofand trisected circumferentially into red, green, and blue transmissionfilters 113 a, 113 b, and 113 c. When the RGB rotary filter is driven torotate by a motor 116, the transmission filters are successivelyinserted into the optical path.

[0314]FIG. 35 shows the characteristics of the red, green, and bluetransmission filters 13 a, 13 b, and 13 c concerning transmission.According to the spectroscopic characteristics of transmission, the red,green, and blue transmission filters 13 a, 13 b, and 13 c transmit lightwith wavelengths permitting excitation of an antibody labeled by ICG aswell as red, green, and blue light rays.

[0315] Light passed by the RGB rotary filter 113 is concentrated by thecondenser 114 and irradiated to the incident end of the light guidefiber 108. The light is propagated along the light guide fiber 108, andemitted from the distal end of the light guide fiber 108 locked in thedistal part 117 of the insertional part 107 to an examined object 119 inthe body cavity through the illumination lens 118 attached to anillumination window.

[0316] When an antibody labeled by ICG is administered as a fluorescentsubstance having an affinity for a lesion such as a carcinoma to theexamined object 119, the fluorescent substance is excited by infraredlight with wavelengths of about 770 to 780 nm. Fluorescence withwavelengths in the infrared spectrum of about 810 to 820 nm isgenerated.

[0317] The distal part 117 has an observation window adjacently to theillumination window. An objective lens 120 is attached to theobservation window. Reflected light and fluorescence stemming from theilluminated examined object 119 are converged to form images at an imageformation position. A CCD 121 is placed as a solid-state imaging deviceat the image formation position. The CCD 121 photoelectrically convertsthe converged light. The objective lens 120 and CCD 121 constitute animaging means.

[0318] In this embodiment, a filter diaphragm 122 exhibiting thecharacteristic of transmission dependent on specified wavelengths isplaced as a diaphragm means for restricting an amount of incident lighton an optical path linking the objective lens 120 and CCD 121. Moreover,an excitation light cutoff filter 123 for cutting off excitation lightis also placed.

[0319] The filter diaphragm 122 is, as shown in FIG. 36, coaxiallytrisected.

[0320] Specifically, the filter diaphragm 122 has a circular visiblelight transmission area 122 a formed along an innermost circumference,an annular visible light non-transmission area 122 b formed outside thearea 122 a, and an annular light interception area 122 c formed outsidethe area 122 b.

[0321]FIG. 37 shows the characteristics of the visible lighttransmission area 122 a, visible light non-transmission area 122 b, andlight interception area 122 c concerning transmission.

[0322] The visible light transmission area 122 a that is the smallestinnermost circular area exhibits a nearly flat characteristic oftransmission in relation to the visible spectrum and infrared spectrum.The visible light non-transmission area 122 b is characteristic of nottransmitting visible light but transmitting light with wavelengths offluorescence in the infrared spectrum. For visible light, since only thevisible light transmission area 122 a that has the smallest sectionalarea or the smallest transmission field transmits the visible light, thefilter diaphragm 122 therefore plays a role of a diaphragm providing asmall magnitude of open. For fluorescence with wavelengths in theinfrared spectrum, since both the visible light transmission area 122 aand visible light non-transmission area 122 transmit the fluorescence,the filter diaphragm 122 plays a role of a diaphragm providing a a largemagnitude of open. Incidentally, the outermost light interception area122 c intercepts visible light and light with wavelengths in theinfrared spectrum.

[0323] As shown in FIG. 38, the excitation light cutoff filter 123 cutsoff light with wavelengths of 700 to 800 nm, and therefore interceptsexcitation light incident on the CCD 121.

[0324] An image signal photoelectrically converted by the CCD 121 issent to a pre-amplifier 124 included in the processor 104A foramplifying a signal, an automatic gain control (AGC) circuit 125 forautomatically controlling the gain of a signal, an A/D conversioncircuit 126, a multiplexer 127 for switching output destinations, afirst frame memory 128 for temporarily storing an image, a second framememory 129, an image processing circuit 130 for carrying out processingsuch as image enhancement, an image display control circuit 131 forcontrolling image display, and a D/A conversion circuit 132, and thenoutput to the monitor 105.

[0325] The processor 104A includes an automatic light adjustment circuit133 for controlling a magnitude of open, by which the illumination lightdiaphragm 112 opens, on the basis of a signal passing through thepre-amplifier 124, and a timing control circuit 134 for synchronizingthe whole of the fluorescent endoscope system 101A.

[0326] A laser guide 137 for routing laser light is connected to thelaser light source 106 for generating laser light for laser therapy. Thelaser guide 137 is structured to be inserted into a forceps channel 136formed in the electronic endoscope 102A.

[0327] An observation mode selection switch is located on a front panelor the like of the processor 104A. Using the observation mode selectionswitch, any of a normal observation mode in which a normal endoscopicimage depicted by visible light is used for observation, a fluorescenceobservation mode in which a fluorescence image depicted by fluorescenceis used for observation, and a fluorescence/normal light observationmode in which the fluorescence image and normal endoscopic image areused for observation can be selected.

[0328] Specifically, when the observation mode selection switch is usedfor selection, an instruction is input to the timing control circuit134. The timing control circuit 134 controls switching of the motors 115and 116 and switching by the multiplexer 127. Thus, control is givenaccording to a selected one of the modes explained in FIGS. 39 to 41.

[0329] For example, when the normal observation mode is selected, thetiming control circuit 134 controls a magnitude of rotation of the motor115 so that the visible light transmission filter 111 a of the spectrumrestriction rotary filter 111 will be locked on the optical path, andcontrols rotation of the motor 116 so that the RGB rotary filter 113will rotate 30 times per second.

[0330] An image signal produced by the CCD 121 under illumination inthis state, that is, under successive illumination of red, green, andblue light is stored in the first frame memory 128 or second framememory 129 by controlling switching by the multiplexer 127.

[0331] Furthermore, when the fluorescence/normal light observation modeis selected, the timing control circuit 134 controls rotation of themotor 115 so that the spectrum restriction rotary filter 111 will rotate90 times per second, and controls rotation of the motor 116 so that theRGB rotary filter 113 will rotate 30 times per second.

[0332] Moreover, image signals representing red light, fluorescence,green light, fluorescence, blue light, and fluorescence and resultingfrom imaging by the CCD 121 performed sequentially under illumination inthe above state, that is, performed under successive illumination ofred, infrared, green, infrared, blue, and infrared light rays arecontrolled by controlling switching by the multiplexer 127 so that imagesignals representing visible light will be stored in the first framememory 128, and image signals representing fluorescence will be storedin the second frame memory 129.

[0333] In this embodiment, a diaphragm means formed with the filterdiaphragm 122 for restricting an amount of incident light is located onthe optical path of the imaging means. The filter diaphragm 122 has thevisible light transmission area 122 a and visible light non-transmissionarea 122 b formed so that the center small circular part of the filterdiaphragm 122 opens to transmit visible light, and the center smallcircular part of the filter diaphragm and the annular part outside thecenter part open to transmit fluorescence. For visible light, an amountof incident light is reduced greatly so that an image demonstrating alarge depth of field can be produced. For fluorescence, the amount ofincident light is not reduced very much so that a bright image can beproduced.

[0334] Next, the operations of the fluorescent endoscope system 101Ahaving the aforesaid components will be described. A fluorescentsubstance having an affinity for a lesion such as a carcinoma, beingexcited with light with wavelengths in the infrared spectrum, andfluorescing in the infrared spectrum, for example, an antibody labeledby ICG is administered to the examined object 119.

[0335] The antibody labeled by ICG is excited with irradiation ofinfrared light with wavelengths of about 770 to 780 nm, and fluorescesin the infrared spectrum of about 810 to 820 nm. When excitation lightis irradiated to inside of a body, a large amount of fluorescenceemanates from a lesion. The presence or absence of the lesion cantherefore be recognized by detecting the fluorescence.

[0336] The lamp 110 in the light source apparatus 103A is a xenon lampand radiates light with wavelengths in a spectrum including the visiblespectrum and the spectrum of wavelengths of excitation light forexciting an antibody labeled by ICG. Light radiated from the lamp 110falls on the spectrum restriction rotary filter 111.

[0337] The spectrum restriction rotary filter 111 is, as shown in FIG.32, composed of a visible light transmission filter 111 a that is a halfof a circular filter disk, and an infrared light transmission filter 111b that is the other half thereof.

[0338] The visible light transmission filter 111 a is a bandpass filterfor, as indicated with the spectroscopic characteristic curve oftransmission drawn with a solid line in FIG. 33, transmitting light withwavelengths in a spectrum including the visible spectrum and thespectrum of wavelengths of red, green, and blue light rays. The infraredlight transmission filter 111 b is a bandpass filter for, as indicatedwith a dashed line, transmitting light with the wavelengths ofexcitation light for exciting an antibody labeled by ICG and cutting offlight with the wavelengths of fluorescence.

[0339] Light passed by the spectrum restriction rotary filter 111 has anamount thereof adjusted by the illumination light diaphragm 112 and thenfalls on the RGB rotary filter 113.

[0340] The RGB rotary filter 113 is, as shown in FIG. 34, composed ofred, green, and blue filters 113 a, 113 b, and 113 c which aretrisections of a filter disk. The spectroscopic characteristics of thefilters concerning transmission are, as shown in FIG. 35, such that thefilters transmit light with wavelengths in the spectrum of wavelengthsof red, green, and blue light rays as well as light with wavelengths inthe spectrum of wavelengths of excitation light for exciting an antibodylabeled by ICG.

[0341] In normal light observation, the visible light transmissionfilter 111 a of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 13 is rotated 30 times persecond. Thus, red, green, and blue light rays are irradiatedsuccessively (See FIG. 39).

[0342] In fluorescence observation, the infrared light transmissionfilter 111 b of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 113 is rotated 30 times persecond. Thus, infrared light with wavelengths in the spectrum ofwavelengths of excitation light is irradiated (See FIG. 40).

[0343] For simultaneously viewing both a fluorescence image and normallight image, the RGB rotary filter 113 is rotated 30 times per secondand the spectrum restriction rotary filter 111 is rotated 90 times persecond. Thus, red light, excitation light, green light, excitationlight, blue light, and excitation light are irradiated successively (SeeFIG. 41).

[0344] At this time, the timing control circuit 134 gives control sothat the RGB rotary filter 113 and spectrum restriction rotary filter111 can rotate synchronously.

[0345] Light transmitted by the RGB rotary filter 113 falls on theincident end of the light guide fiber 108 in the electronic endoscope102A, and propagates along the light guide fiber 108. The light is thenirradiated from the distal end of the light guide fiber 108 to theexamined object 119. The optical systems in the electronic endoscope 102and light source apparatus 103A are designed to cope with light withwavelengths in the infrared spectrum. In the examined object 119,irradiated light is absorbed or reflected by a living tissue, andfluorescence is emitted from the administered fluorescent substanceaccumulated in a lesion.

[0346] Reflected light and fluorescence stemming from the examinedobject 119 is passed by the filter diaphragm 122 and excitation lightcutoff filter 123 placed on the optical path, and then imaged by the CCD121. The filter diaphragm 122 is, as shown in FIG. 36, composed of thevisible light transmission area 122 a, visible light non-transmissionarea 122 b, and light interception area 122 c. The areas exhibit thespectroscopic characteristics of transmission shown in FIG. 37.

[0347] The visible light non-transmission area 122 b does not transmitvisible light but transmit light with wavelengths in the spectrum ofwavelengths of fluorescence within the infrared spectrum. For visiblelight, since the visible light transmission area 122 a alone of thefilter diaphragm 122 transmits light, the filter diaphragm 122 serves asa diaphragm providing a small magnitude of open. For infraredfluorescence, since both the visible light transmission area 122 a andvisible light non-transmission area 122 b transmit light, the filterdiaphragm 122 serves as a diaphragm providing a large magnitude of open.

[0348] In normal light (visible light) observation, a sharp visiblelight image demonstrating a large depth of field is formed on the CCD121. In fluorescence observation, a bright fluorescence image is formedon the CCD 121. In normal light observation using visible light, a sharpimage is needed for identifying a lesion in terms of the color or shapeof a living tissue. However, fluorescence observation is regarded asassessment of presence. In fluorescence observation, presence or absenceof a lesion is merely detected by checking the level of brightness of animage. It is therefore required to produce a brighter image other than asharp image demonstrating a high spatial resolution. This embodimentsatisfies this requirement.

[0349] The excitation light cutoff filter 123 is designed to cut offexcitation light components emanating from an antibody labeled by ICG,and to transmit fluorescence components and visible light components.The excitation light cutoff filter 123 exhibits the spectroscopiccharacteristic of transmission shown in FIG. 38.

[0350] The CCD 121 receives red, green, and blue visible light rays orinfrared fluorescence according to the positions of the RGB rotaryfilter 113 and spectrum restriction rotary filter 111. The CCD 121 isdriven synchronously with the rotations of the RGB rotary filter 113 andspectrum restriction filter 111 by means of a CCD drive circuit that isnot shown, and forms 180 frame images or 90 frame images per secondaccording to whether or not the spectrum restriction rotary filter 111has rotated (See FIGS. 39 to 41).

[0351] An electric signal output from the CCD 121 is input to thepreamplifier 124 in the processor 104A. After amplified, the gain of thesignal is controlled by the AGC circuit 125. Thereafter, the signal isinput to the A/D conversion circuit 126 and converted into a digitalsignal. The digital signal is stored in the first frame memory 128 orsecond frame memory 129 selected by the multiplexer 127.

[0352] Based on a control signal sent from the timing control circuit134, the multiplexer 127 routes a signal, which is produced with thevisible light transmission area 111 a of the spectrum restriction rotaryfilter 111 inserted to the optical path, to the first frame memory 128,and routes a signal, which is produced with the infrared lighttransmission area 111 b inserted thereto, to the second frame memory129.

[0353] The first and second frame memories 128 and 128 are each composedof three frame memories that are not shown. An image formed with the redfilter 113 a of the RGB rotary filter 113 inserted to the optical path,an image formed with the green filter 113 b thereof inserted thereto,and an image formed with the blue filter 113 c inserted thereto arerecorded in the three frame memories respectively.

[0354] The three frame memories are read simultaneously, wherebycolor-sequential images sent time-sequentially are timed. Signals outputfrom the first and second frame memories 128 and 129 are input to theimage processing circuit 130, and subjected to image processing such asimage enhancement and noise elimination. The resultant signals are inputto the image display control circuit 131 and controlled for simultaneousdisplay of a fluorescence image, normal light image, and characterinformation.

[0355] A digital signal output from the image display control circuit131 is input to the D/A conversion circuit 132, converted into an analogsignal, and then output to the monitor 5. The automatic light adjustmentcircuit 133 sends a signal for use in controlling the illumination lightdiaphragm 112 so that illumination light of proper brightness can beirradiated. The timing control circuit 134 synchronizes rotations of theRGB rotary filter 113 and spectrum restriction filter 111, drive of theCCD, and various kinds of video signal processing.

[0356] On the monitor 105, depending on the position of the spectrumrestriction rotary filter 111, a normal light image or fluorescenceimage can be viewed or both of them can be viewed simultaneously.

[0357] In this case, the normal light image displayed on the displaysurface of the monitor 105 is a sharp image demonstrating a large depthof field. By contrast, the fluorescence image is a bright image andhelpful in diagnosis.

[0358] In this embodiment, both a normal light image and fluorescenceimage can be produced simultaneously. The embodiment therefore has themerit that an endoscope can be positioned easily for further observing aregion, which is suspected to contain a lesion and observed in thefluorescence image, using a normal light image.

[0359] For laser therapy, laser light is emitted from the laser lightsource 106. The emitted laser light is irradiated to a lesion throughthe laser guide 137. The laser light source 106 is a semiconductor laserand emits laser light whose wavelengths are matched with those ofexcitation light for exciting an antibody labeled by ICG.

[0360] It will therefore not take place that a fluorescence image ornormal light image is disturbed greatly with irradiation of laser light.Moreover, since laser light is well-absorbed by an antibody labeled byICG, a lesion can be treated efficiently.

[0361] In this embodiment, a single lamp is used as a light source meansfor observation. Alternatively, two or more light sources, for example,a halogen lamp for normal light observation and a laser orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0362] Moreover, illumination light for exciting a fluorescent substancemay be irradiated in vitro.

[0363] Moreover, the function for cutting off excitation light is notlimited to the one located on the face of the CCD 121 but may be locatedon the objective lens 120 or filter diaphragm 122.

[0364] The position of the CCD 121 is not limited to the position in thedisplay part 117 of the insertional part 107 of the electronic endoscope102A. Alternatively, the CCD 121 may be placed inside the processor 104Aand light may be routed by the image guide filter. Otherwise, the CCD121 may be placed in the camera head that is attachable or detachable toor from the optical endoscope.

[0365] Moreover, an image intensifier may be located on the face of theCCD 121 in order to improve sensitivity.

[0366] Moreover, field-by-field processing may be adopted instead offrame-by-frame processing.

[0367] This embodiment has the advantages described below.

[0368] Since the area of a diaphragm for transmitting fluorescence ismade larger than the area thereof for transmitting visible light (normallight), a large amount of fluorescence can be passed by the diaphragm.An image depicted by the fluorescence therefore gets brighter. An imagedepicted by the normal light demonstrates a larger depth of field.

[0369] Next, the eighth embodiment of the present invention will bedescribed.

[0370] An object of this embodiment is to provide a fluorescentendoscope system making it possible to view a brighter image littleaffected by a noise under fluorescence, and to view an image with alittle blur, which demonstrates a larger depth of field, under normallight.

[0371] The eighth embodiment is configured similarly to the seventhembodiment. Differences will be described mainly. The same referencenumerals will be assigned to the components having similar functions,and the description of the components will be omitted.

[0372] A fluorescent endoscope system 101B of the eighth embodimentshown in FIG. 42 is different from the fluorescent endoscope system 101Ashown in FIG. 31 in points that an electronic endoscope 102B adopts aliquid-crystal diaphragm 138 using a liquid crystal in place of thefilter diaphragm 122 included in the electronic endoscope 102A, that alight source apparatus 103B does not include the spectrum restrictionfilter 111 included in the light source apparatus 103A but employs aparallel rotary filter 139 for restricting wavelengths of transmittedlight in place of the RGB rotary filter 113, and that a processor 104Bhas red, green, and blue memories 141 a, 141 b, and 141 c in place ofthe first frame memory 128 and second frame memory 129 included in theprocessor 104A and includes three integration circuits 142.

[0373] The parallel rotary filter 139 in the light source apparatus 103Bis driven to rotate by a motor 140. The motor 140 is controlled by thetiming control circuit 134 so that the rotating speed will remainconstant. The parallel rotary filter 139 has, as shown in FIG. 43, red,green and blue filters 139 a, 139 b, and 139 c along the outercircumference thereof and has three infrared filters 139 d along theinner circumference thereof. The parallel rotary filter 139 is movablein directions orthogonal to the axis of rotation (vertical directions inFIG. 42). In normal observation, the red, green, and blue filters 139 a,139 b, and 139 c formed along the outer circumference are inserted intothe optical path. In fluorescence observation, the infrared filters 139d formed along the inner circumference are inserted.

[0374] The red, green, and blue filters 139 a, 139 b, and 139 c, and theinfrared filters 139 d exhibit the characteristics of transmission shownin FIG. 44. The red, green, and blue filters 139 a, 139 b, and 139 ctransmit red, green, and blue light components, and the infrared filters139 d transmit excitation light components for exciting an antibodylabeled by ICG.

[0375] The liquid-crystal diaphragm 138 located on the optical pathbetween the objective lens 120 and CCD 121 in the electronic endoscope102B and designed for restricting an amount of transmitted light is, asshown in FIG. 45, concentrically divided into three portions.

[0376] Specifically, as shown in FIG. 45, the liquid-crystal diaphragm138 is composed of an aperture 138 a, liquid-crystal plate 138 b, andlight interceptor 138 c in that order concentrically from the centerthereof. A voltage to be applied to the liquid-crystal plate 138 b iscontrolled by the timing control circuit 134.

[0377] The liquid-crystal plate 138 b has the property of nottransmitting light when a voltage is applied to the liquid-crystal platebut transmitting light when no voltage is applied thereto. When avoltage is applied, an opening provided by the diaphragm gets smaller,and a sharp image demonstrating a large depth of fields is formed on theCCD 121. When no voltage is applied, the opening provided by thediaphragm gets larger. A bright image is therefore formed on the CCD121.

[0378] The processor 104B includes, like the one shown in FIG. 31, thepreamplifier 124, AGC circuit 125, A/C conversion circuit 126, andmultiplexer 127. A signal input to the multiplexer 127 is routed to thered memory 141 a, green memory 141 b, or blue memory 141 c.

[0379] Output signals of the red memory 141 a, green memory 141 b, andblue memory 141 c are input to the image processing circuit 130 via theintegration circuits 142. An output of the image processing circuit 130is, like that of the one shown in FIG. 31, output to the monitor 105 viathe image display control circuit 131 and D/A conversion circuit 132.

[0380] The processor 104B includes the timing control circuit 134 forsynchronizing the automatic light adjustment circuit 133 and the wholeof the fluorescent endoscope system 101B and for controlling therotation of the parallel rotary filter 139 and the operations of theliquid-crystal diaphragm 138 and integration circuits 142.

[0381] The integration circuits 142 are, as shown in FIG. 46, eachcomposed of two multipliers 143 and 146 whose coefficients can berewritten, an adder 144, and a frame memory 145.

[0382] Moreover, the laser light source 106 for generating laser lightused for laser therapy and the laser guide 137 along which the laserlight is routed are included.

[0383] Next, the operations of the fluorescent endoscope system 101Bhaving the foregoing components will be described.

[0384] A fluorescent substance having an affinity for a lesion such as acarcinoma, such as, an antibody labeled by ICG is administered inadvance to the examined object 119.

[0385] The lamp 110 in the light source apparatus 103B radiates lightwith wavelengths in a spectrum including the visible spectrum and aspectrum of wavelengths of excitation light for exciting the antibodylabeled by ICG. The light radiated from the lamp 110 has the amountthereof adjusted by the illumination light diaphragm 112 and is thentransmitted by the parallel rotary filter 139.

[0386] The light transmitted by the parallel rotary filter 139 falls onthe incident end of the light guide fiber 108 of the electronicendoscope 102B. The parallel rotary filter 139 has, as shown in FIG. 43,the red filter 139 a, green filter 139 b, and blue filter 139 c, whichtransmit red, green, and blue light rays respectively with wavelengthsin the visible spectrum, formed along the outer circumference thereof,and has the infrared filters 139 d, which transmit light withwavelengths in the infrared spectrum, formed along the innercircumference thereof.

[0387] The filters have the characteristics of transmission shown inFIG. 44. The infrared filters 139 d transmit excitation light componentsfor exciting an antibody labeled by ICG. During operation, the parallelrotary filter 139 rotates 30 times per second. The parallel rotaryfilter 139 is movable in directions perpendicular to the axis ofrotation. In normal light observation, the red, green, and blue filters139 a, 139 b, and 139 c formed along the outer circumference areinserted into the path of illumination light, whereby red, green, andblue light rays are irradiated successively to the object. Influorescence observation, the infrared filters 139 d formed along theinner circumference are inserted into the path of illumination light,whereby infrared light with wavelengths in the spectrum of wavelengthsof excitation light is irradiated.

[0388] Reflected light and fluorescence stemming from the examinedobject 119 are passed by the liquid-crystal diaphragm 138 and excitationlight cutoff filter 123 and then imaged by the CCD 121. Theliquid-crystal diaphragm 138 is, as shown in FIG. 45, composed of theaperture 138 a, liquid-crystal plate 138 b, and light interceptor 138 cwhich are arranged in that order concentrically from the center. Avoltage to be applied to the liquid-crystal plate 138 b is controlled bythe timing control circuit 134. The liquid-crystal plate 138 b has theproperty of not transmitting light when a voltage is applied thereto buttransmitting light when no voltage is applied thereto.

[0389] As shown in FIG. 47, in normal observation, a voltage is applied.Consequently, the diaphragm provides a small opening, and a sharp imagedemonstrating a large depth of field is formed on the CCD 121. Moreover,in fluorescence observation, no voltage is applied. Consequently, thediaphragm provides a large opening, and a bright image is formed on theCCD 121.

[0390] The excitation light cutoff filter 123 is designed to cut offexcitation light components for exciting an antibody labeled by ICG andto transmit fluorescence components and visible light components. Theexcitation light cutoff filter exhibits the spectroscopic characteristicof transmission shown in FIG. 38.

[0391] The CCD 121 receives visible light rays of red, green, and blueor infrared fluorescence depending on the position of the parallelrotary filter 139. The CCD 121 is driven by a CCD drive circuit that isnot shown synchronously with the rotation of the parallel rotary filter139. In normal light observation, the CCD 121 forms 90 frame images persecond. In fluorescence observation, the CCD 121 forms 30 frame imagesper second (See FIG. 47).

[0392] In fluorescence observation, the exposure time of the CCD 121 ismade longer (three times longer in FIG. 47) than that in normal lightobservation in order to produce a brighter image.

[0393] An electric signal output from the CCD 121 is input to thepreamplifier 124 in the processor 104B. After amplified, the gain of thesignal is controlled by the AGC circuit 125. Thereafter, the signal isinput to the A/D conversion circuit 126 and thus converted into adigital signal. The digital signal is stored to any of the three framememories of the red memory 141 a, green memory 141 b, and blue memory141 c selected by the multiplexer 127.

[0394] Based on a control signal sent from the timing control circuit,the multiplexer 127 routes an input signal to the red memory 141 a whenthe red filter 139 a of the parallel rotary filter 139 is inserted intothe optical path, to the green memory 141 b when the green filter 139 bor infrared filter 139 d is inserted thereto, or to the blue memory 141c when the blue filter 139 c is inserted thereto.

[0395] Data items carried by image signals sent from the three framememories 141 a, 141 b, and 141 c are read simultaneously, whereby colorsequential images sent time-sequentially are timed. The digital signalsoutput from the frame memories 141 a, 141 b, and 141 c are subjected tonoise elimination and amplification by means of the integration circuits142.

[0396] The integration circuits 142 each have the configuration of arecursive filter shown in FIG. 46. An input image signal is multipliedby m(1−a) by means of the multiplier 143, and then input to the adder144. The resultant signal is therefore added to an output of themultiplier 146 that multiplies an input by a. An output of the adder 144is input to the frame memory 145 and also input to the image processingcircuit 130.

[0397] In the frame memory 145, an image is delayed by one frame andthen output. The coefficients set in the two multipliers 143 and 145 canbe rewritten in response to a coefficient rewrite signal output from thetiming control circuit 134.

[0398] In the recursive filter, the coefficient m denotes anamplification factor. The larger the coefficient m is, the brighter aproduced image is. The larger a results in a greater effect of anafterimage. Consequently, a noise in an image is reduced.

[0399] In this embodiment, as shown in FIG. 47, the coefficient m is setto 1 for normal light observation and set to 2 for fluorescenceobservation. Thus, a brighter image can be produced under fluorescence.The coefficient a is set to 0.1 for normal light observation and to 0.5for fluorescence observation. Thus, in fluorescence observation, a noiseis reduced to a greater extent.

[0400] A clipping circuit for preventing a result of multiplication frombecoming an overflow is incorporated in the multiplier 143.

[0401] Signals output from the integration circuits 142 are input to theimage processing circuit 130 and subjected to image processing such asimage enhancement. The resultant signals are input to the image displaycontrol circuit 131 and controlled for display of character information.A digital signal output from the image display control circuit 131 isinput to the D/A conversion circuit 132, and converted into an analogsignal. The analog signal is output to the monitor 105.

[0402] The automatic light adjustment circuit 133 sends a signal for usein controlling the illumination light diaphragm 112 so that illuminationlight of proper brightness can be irradiated. The timing control circuit134 synchronizes rotation of the parallel rotary filter 139, drive ofthe CCD, and processing of various video signals, and controls a voltageto be applied to the liquid-crystal diaphragm 138 and the coefficientsset in the multipliers 143 and 146 according to switching of visiblelight and infrared light by the parallel rotary filter 139.

[0403] In normal light observation using visible light, a voltage isapplied to the liquid-crystal diaphragm 138 so that the diaphragm canprovide a smaller opening. This results in a sharp image demonstrating alarge depth of field. Moreover, values permitting suppression of a blureven when an object makes a quick motion are assigned to thecoefficients set in the multipliers 143 and 146. For example, 1 and 0.1are assigned to the coefficients m and a respectively.

[0404] In fluorescence observation using infrared light, no voltage isapplied to the liquid-crystal diaphragm 138 so that the diaphragm canprovide a larger opening. This results in a bright image. Moreover,values permitting exertion of a great effect of noise elimination and aneffect of amplification are assigned to the coefficients set in themultipliers 143 and 146. For example, 2 and 0.5 are assigned to thecoefficients m and a respectively.

[0405] On the monitor 105, depending on the position of the parallelrotary filter 139, a normal light image or fluorescence image can beviewed.

[0406] In this embodiment, a single lamp is employed as a light sourcemeans for observation. Alternatively, two or more light sources, forexample, a halogen lamp for normal light observation and a laser orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0407] Moreover, illumination light for exciting a fluorescent substancemay be irradiated in vitro.

[0408] Moreover, the position of the CCD 121 is not limited to theposition in the distal part 117 of the insertional part 107.Alternatively, the CCD 121 may be incorporated in the processor 104B andlight may be introduced using an image guide fiber. Otherwise, the CCD121 may be placed in the camera head attachable or detachable to or fromthe optical endoscope.

[0409] Moreover, an image intensifier may be placed on the face of theCCD 121, thus improving sensitivity.

[0410] Moreover, a diaphragm employed is not limited to a liquid-crystaldiaphragm but may be a diaphragm made of a shape memory alloy.Alternatively, a light interceptive member may be thrust and plungedmechanically.

[0411] Moreover, the three filters 139 d for excitation (formed alongthe inner circumference) of the parallel rotary filter 139 are notlimited to filters having the same characteristic of transmission suchas the ones in this embodiment. Alternatively, for example, one of thefilters may be designed to transmit light with wavelengths of about 900nm and to thus receive reflected light of infrared.

[0412] Owing to this configuration, an image made by superposing areflected light image depicted by light with wavelengths of about 900 nmon a fluorescence image can be viewed on the monitor. It will thereforenot take place that a region in which an antibody labeled by ICG is notaccumulated is seen completely dark. When the endoscope is manipulatedwhile a fluorescence image is viewed, or when the endoscope is used fora treatment, safety can be guaranteed readily.

[0413] This embodiment has the advantages described below.

[0414] Since a diaphragm is controlled responsively to switching offluorescence observation and normal light observation, a brighter imagecan be used for observation in fluorescence observation, and an imagedemonstrating a large depth of field can be used for observation innormal light observation.

[0415] Moreover, the coefficients set in a recursive filter are changedresponsively to switching of fluorescence observation and normal lightobservation. Fluorescence can be observed while little affected by anoise. Normal light can be observed in line with the quick motion of anobject.

[0416] Moreover, the exposure time of the CCD 21 is varied responsivelyto switching of fluorescence observation and normal light observation.An object emitting feeble fluorescence can be observed more brightly.

[0417] Next, the ninth embodiment will be described.

[0418] An object of this embodiment is to provide a fluorescentendoscope system making it possible to observe an object, from whichboth fluorescence and normal light originate, at proper brightness.

[0419] This embodiment is configured similarly to the seventhembodiment. Differences will be described mainly. The same referencenumerals will be assigned to components having similar functions. Thedescription of the components will be omitted.

[0420] A fluorescent endoscope system 101C of the ninth embodiment isdifferent from the fluorescent endoscope system 101A shown in FIG. 31 inpoints that an electronic endoscope 102C adopts a CCD 151 capable ofvarying an amplification factor internally in place of the CCD 121employed in the electronic endoscope 102A, and adopts a diaphragm 152for restricting an amount of transmitted light in place of the filterdiaphragm 122, that a light source apparatus 103C includes a lamp lightemission control circuit 153 for controlling glowing of a lamp 110 inaddition to the components of the light source apparatus 103A, and thata processor 104C includes a CCD drive circuit 154 for controlling theCCD 151 in addition to the components of the processor 104A.

[0421] The light source apparatus 103C includes, like the one shown inFIG. 31, the lamp 110 for radiating light, the spectrum restrictionrotary filter 111 located on the path of illumination light forrestricting the wavelengths of transmitted light, the illumination lightdiaphragm 112 for restricting an amount of light, the RGB rotary filter113 for restricting the wavelengths of transmitted light, the condenser114, and the lamp light emission control circuit 153 for controllingglowing of the lamp 110.

[0422] The spectrum restriction rotary filter 111 is, as shown in FIG.32, bisected into the visible light transmission filter 111 a andinfrared light transmission filter 111 b. The RGB rotary filter 113 is,as shown in FIG. 34, trisected into the red, green, and blue filters 113a, 113 b, and 113 c.

[0423] The electronic endoscope 102C includes the light guide filter 108over which illumination light is propagated, the illumination lens 118opposed to the distal end of the light guide fiber 108, a diaphragm forrestricting an amount of passed light, the excitation light cutofffilter.123 for removing excitation light, and the CCD 151 in which anamplification factor is variable.

[0424] The processor 104C includes the preamplifier 124, AGC circuit125, A/D conversion circuit 126, multiplexer 127, first frame memory128, second frame memory 129, image processing circuit 130 for carryingout processing such as image enhancement, image display control circuit131, D/A conversion circuit 132, automatic light adjustment circuit 133for controlling the illumination light diaphragm 112, timing controlcircuit for synthesizing all the components of the fluorescent endoscopesystem 101C, and CCD drive circuit 154 for controlling the CCD 151.

[0425] Moreover, the laser light source 106 for generating laser lightfor the purpose of laser therapy and the laser guide 137 for guidinglaser light are included.

[0426] Next, the operations of the fluorescent endoscope system 101Chaving the foregoing components will be described. A fluorescentsubstance having an affinity for a lesion such as a carcinoma, such as,an antibody labeled by ICG is administered to the examined object 119 inadvance.

[0427] Light with wavelengths in a spectrum including the visiblespectrum and the spectrum of wavelengths of excitation light forexciting the antibody labeled by ICG is radiated from the lamp 110 inthe light source apparatus 103C. The light radiated from the lamp 110 ispassed by the spectrum restriction rotary filter 111 and illuminationlight diaphragm 112, and transmitted by the RGB rotary filter 113. Thelight passed by the RGB rotary filter 113 falls on the light guidefilter 108 of the electronic endoscope 102C.

[0428] The spectrum restriction rotary filter 111 has the structureshown in FIG. 32, and exhibits the spectroscopic characteristics oftransmission shown in FIG. 33. The RGB rotary filter 113 has thestructure shown in FIG. 34, and exhibits the spectroscopiccharacteristics of transmission shown in FIG. 35.

[0429] In normal light observation, as shown in FIG. 49, the lamp lightemission control circuit 153 supplies a pulsating current of, forexample, 18 A to the lamp the lamp 110 glows synchronously with therotation of the RGB rotary filter 113.

[0430] The visible light transmission filter 111 a of the spectrumrestriction rotary filter 111 is locked on the optical path. The RGBrotary filter 113 is rotated 30 times per second. Thus, red, green, andblue light rays are irradiated successively (See FIG. 49).

[0431] In fluorescence observation, the lamp light emission controlcircuit 153 supplies, as shown in FIG. 50, a pulsating current of 21 A.The lamp 110 glows synchronously with the rotation of the RGB rotaryfilter 113.

[0432] The infrared light transmission filter 111 b of the spectrumrestriction rotary filter 111 is locked on the optical path, and the RGBrotary filter 113 is rotated 30 times per second. Thus, infrared lightwith wavelengths in the spectrum of wavelengths of excitation light isirradiated (See FIG. 50).

[0433] In fluorescence/normal light simultaneous observation, as shownin FIG. 51, the lamp light emission control circuit 153 supplies apulsating current of 21 A or 18 A according to the position of thespectrum restriction rotary filter 111. The lamp 110 glows synchronouslywith the rotation of the RGB rotary filter 113.

[0434] The RGB rotary filter 113 is rotated 30 times per second and thespectrum restriction rotary filter 111 is rotated 90 times per second.Thus, red light, excitation light, green light, excitation light, bluelight, and excitation light are irradiated successively (See FIG. 51).

[0435] At this time, the timing control circuit 134 gives control sothat the RGB rotary filter 113 and spectrum restriction rotary filter111 will rotate mutually synchronously. The lamp light emission controlcircuit 153 gives control so as to supply a given current to the lamp110 responsively to switching of the portions of the spectrumrestriction rotary filter 111.

[0436] As mentioned above, a larger current than the current to besupplied in normal light observation is supplied in fluorescenceobservation. Thus, the intensity of fluorescence can be increased, and abright fluorescence image can be produced.

[0437] Reflected light and fluorescence stemming from the examinedobject 119 are passed by the diaphragm 152 for restricting an amount oflight and excitation light cutoff filter 123, and imaged by the CCD 151.The excitation light cutoff filter 123 is designed to cut off excitationlight components for exciting the antibody labeled by ICG and transmitfluorescence components and visible-light components. The excitationlight cutoff filter 123 exhibits the spectroscopic characteristic oftransmission shown in FIG. 38. The CCD 151 therefore receives red,green, and blue visible light rays or infrared fluorescence according tothe positions of the RGB rotary filter 113 and spectrum restrictionrotary filter 111.

[0438] The CCD 151 employed in this embodiment can provide a highamplification factor owing to an avalanche effect. The amplificationfactor is controlled on the basis of the amplitude of a clock. Sinceamplification is achieved inside the CCD 151, the amplification islittle affected by an extraneous noise. When the amplification factor israised by increasing the amplitude of the clock, even if light stemmingfrom a region is feeble, the region can be observed brightly.

[0439] The CCD 151 is driven synchronously with the rotations of therotary filters 111 and 113 by means of the CCD drive circuit 154.Depending on whether or not the spectrum restriction rotary filter 111is rotated, the CCD 151 forms 180 frame images or 90 frame images persecond. When the visible light transmission filter 111 a of the spectrumrestriction rotary filter 111 is inserted (in normal light observation),the CCD drive circuit 154 reduces the amplitude of the clock so as tolower the amplification factor in the CCD 151 (See FIGS. 49 and 51).

[0440] In observation using normal light, a relatively bright image canbe produced. A low amplification factor will therefore do. When theinfrared light transmission filter 111 b is inserted (in fluorescenceobservation), the amplitude of the clock is increased in order to raisethe amplification factor in the CCD 151 (See FIGS. 50 and 51).

[0441] By raising the amplification factor, even a region from whichfeeble fluorescence originates can be observed at sufficient brightness.

[0442] An electric signal output from the CCD 151 is input to andamplified by the preamplifier 124 in the processor 104C. The gain of thesignal is controlled by the AGC circuit 125. Thereafter, the signal isinput to the A/D conversion circuit 126 and converted into a digitalsignal.

[0443] The digital signal is stored in the first frame memory 128 orsecond frame memory 129 selected by the multiplexer 127. Based on acontrol signal sent from the timing control circuit 134, when thevisible light transmission filter 111a of the spectrum restrictionrotary filter 111 is inserted to the optical path, the multiplexer 127selects the first frame memory 128. When the infrared light transmissionfilter 111 b is inserted thereto, the multiplexer 127 selects the secondframe memory 129.

[0444] Signals output from the first and second frame memories 128 and129 are input to the image processing circuit 130 and subjected to imageprocessing such as image enhancement and noise elimination. A resultantsignal is then input to the display control circuit 131 and thuscontrolled for simultaneous display of a fluorescence image, a normallight image, and character information.

[0445] A digital signal output from the image display control circuit131 is input to the D/A conversion circuit 132 and converted into ananalog signal. The analog signal is then output to the monitor 5. Theautomatic light adjustment circuit 133 sends a signal for use incontrolling the illumination light diaphragm 112 so that illuminationlight of proper brightness can be irradiated. The timing control circuit134 synchronizes and controls rotations of the rotary filters, drive ofthe CCD, processing of various video signals, and glowing of the lamp.

[0446] In this embodiment, the single lamp 110 is employed as a lightsource for observation. Alternatively, two or more light sources, forexample, a halogen lamp for normal line observation and a laser orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0447] Moreover, illumination light for use in exciting a fluorescentsubstance may be irradiated in vitro.

[0448] Moreover, a means for controlling an amount of illumination lightis not limited to the mechanism for varying a current to be supplied tothe lamp. Alternatively, the opening provided by an illumination lightdiaphragm may be controlled or a filter for restricting an amount oflight may be inserted to the path of illumination light.

[0449] Moreover, the position of the CCD 151 is not limited to theposition in the distal part 117 of the insertional part 7.Alternatively, the CCD 151 may be incorporated in the processor 104C,and light may be introduced over an image guide fiber. Otherwise, theCCD 151 may be incorporated in the camera head attachable or detachableto or from the optical endoscope.

[0450] This embodiment has the advantage described below.

[0451] An amount of light emanating from the lamp and an amplificationfactor in the CCD 151 are controlled responsively to switching offluorescence observation and normal light observation. It will not takeplace that a fluorescence image and normal light image are mutuallygreatly different in brightness. Both fluorescence and normal light canbe observed at proper brightness

[0452] Next, the tenth embodiment of the present invention will bedescribed.

[0453] An object of this embodiment is to provide a fluorescentendoscope system capable of removing light, which leaks in from outsideduring fluorescence observation, and producing a fluorescence imagelittle affected by a noise.

[0454] This embodiment is configured similarly to the seventhembodiment. Differences will be described mainly. The same referencenumerals will be assigned to components having similar functions. Thedescription of the components will be omitted.

[0455] A fluorescent endoscope system 101D of the tenth embodiment shownin FIG. 52 is different from the fluorescent endoscope system 101A shownin FIG. 31 in points that an electronic endoscope 102D adopts adiaphragm 152 in place of the filter diaphragm 122 included in theelectronic endoscope 102A, that a processor 104D has a red memory 141 a,green memory 141 b, blue memory 141 c, red′ memory 161 a, green′ memory161 b, and blue′ memory 161 c in place of the first frame memory 128 andsecond frame memory 129 included as the output stage of the multiplexerin the processor 104A, and includes two subtracters 162 and 163, anadder 164, and an integration circuit 142, and that a light sourceapparatus 103D employs an RGB rotary filter 165 having a characteristicdifferent from the characteristic of the RGB rotary filter 113 includedin the light source apparatus 103A.

[0456] The light source apparatus 103D includes, like the one shown inFIG. 31, the lamp 110 for radiating light, the spectrum restrictionrotary filter 111 located on the path of illumination light forrestricting the wavelengths of transmitted light, the illumination lightdiaphragm 112 for restricting an amount of light, and the RGB rotaryfilter 165 having a characteristic different from the characteristic ofthe RGB rotary filter 113 shown in FIG. 31 and restricting thewavelengths of transmitted light.

[0457] The spectrum restriction rotary filter 111 is, as shown in FIG.32, bisected into the visible light transmission filter 111 a andinfrared light transmission filter 111 b. The RGB rotary filter 165 is,as shown in FIG. 53, trisected into a red, green, and blue filters 165a, 165 b, and 165 c. The electronic endoscope 102D includes the lightguide fiber 108 over which illumination light is propagated, thediaphragm 152 for restricting an amount of light falling on an imagingmeans, the excitation light cutoff filter 123 for removing excitationlight, and the CCD 121.

[0458] The processor 104D includes the preamplifier 124, AGC circuit125, A/D conversion circuit 126, multiplexer 127, red memory 141 a,green memory 141 b, blue memory 141 c, red′ memory 161 a, green′ memory161 b, blue′ memory 161 c, two subtracters 162 and 163, adder 164,integration circuit 142, image processing circuit 130, image displaycontrol circuit 131, D/A conversion circuit 132, automatic lightadjustment circuit 133 for controlling the illumination light diaphragm112, and timing control circuit 134 for synchronizing all the componentsof the fluorescent endoscope system 101D.

[0459] Moreover, the laser light source 106 for generating laser lightfor the purpose of laser therapy and the laser guide 137 over whichlaser light is introduced are included.

[0460] Next, the operations of the fluorescent endoscope system 101Dhaving the foregoing components will be described.

[0461] A fluorescent substance having an affinity for a lesion such as acarcinoma, such as, an antibody labeled by indocyanine green (ICG) isadministered to the examined object 119.

[0462] Light with wavelengths in a spectrum including the visiblespectrum and the spectrum of wavelengths of excitation light forexciting the antibody labeled by ICG is radiated from the lamp 110 inthe light source apparatus 103D. The light radiated from the lamp 110 ispassed by the spectrum restriction rotary filter 111 and illuminationlight diaphragm 112, and transmitted by the RGB rotary filter 165.

[0463] The light transmitted by the RGB rotary filter 165 falls on thelight guide fiber 108 of the electronic endoscope 102D. The spectrumrestriction rotary filter 111 has the structure shown in FIG. 32, andexhibits the spectroscopic characteristics of transmission shown in FIG.33. The RGB rotary filter 165 has the structure shown in FIG. 53, andexhibits the spectroscopic characteristics of transmission shown in FIG.54.

[0464] Specifically, the red filter 165 a and green filter 165 btransmit excitation light components of infrared light for exciting anantibody labeled by ICG, but the blue filter 165 c does not transmit theexcitation light components. When the infrared light transmission filter111 b of the spectrum restriction rotary filter 111 is inserted to thepath of illumination light, if the red filter 165 a or green filter 165b is inserted, the excitation light components are irradiated. However,if the blue filter 165 c is inserted, no light is irradiated.

[0465] In normal light observation, the visible light transmissionfilter 111 a of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 165 is rotated 30 times persecond. Thus, red, green, and blue light rays are irradiatedsuccessively (See FIG. 55).

[0466] In fluorescence observation, the infrared light transmissionfilter 111 b of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 165 is rotated 30 times persecond. Thus, infrared light with wavelengths in the spectrum ofwavelengths of excitation light is irradiated intermittently (See FIG.56).

[0467] In fluorescence/normal light simultaneous observation, the RGBrotary filter 165 is rotated 30 times per second and the spectrumrestriction rotary filter 111 is rotated 90 times per second. Thus, redlight, excitation light, green light, excitation light, blue light, andexcitation light are irradiated in that order (See FIG. 57).

[0468] At this time, the timing control circuit 134 gives control sothat the RGB rotary filter 165 and spectrum restriction rotary filter111 can be rotated synchronously.

[0469] Reflected light and fluorescence stemming from the examinedobject 119 are passed by the diaphragm 152 for restricting an amount oflight and the excitation light cutoff filter 123, and then imaged by theCCD 121. The excitation light cutoff filter 123 is designed to cut offexcitation light components for exciting an antibody labeled by ICG andto transmit fluorescence components and visible light components. Thediaphragm 152 exhibits the spectroscopic characteristic of transmissionshown in FIG. 38.

[0470] The CCD 121 therefore receives red, green, and blue visible lightrays, fluorescence of infrared light, or light leaking in from outsidethe body and resulting in a noise according to the positions of the RGBrotary filter 165 and spectrum restriction rotary filter 111 (See FIGS.55 to 57).

[0471] The CCD 121 is driven synchronously with the rotations of therotary filters 111 and 165 by means of a CCD drive circuit that is notshown, and forms 180 frame images or 90 frame images per seconddepending on whether or not the spectrum restriction rotary filter 111is rotated.

[0472] An electric signal output from the CCD 121 is input to andamplified by the preamplifier 124 in the processor 104D. The gain of thesignal is controlled by the AGC circuit 125. Thereafter, the signal isinput to the A/D conversion circuit 126 and converted into a digitalsignal.

[0473] The digital signal is stored in any of the six frame memories 141a to 141 c and 161 a to 161 c selected by the multiplexer 127. Themultiplexer 27 selects a memory, in which an image is stored, on thebasis of a control signal sent from the timing control circuit 134.

[0474] When the visible light transmission filter 111 a of the spectrumrestriction rotary filter 111 is inserted to the path of illuminationlight, an image signal is stored in the red memory 141 a, green memory141 b, or blue memory 141 c according to the position of the RGB rotaryfilter 165. In other words, an image formed under light irradiatedthrough the red filter is stored in the red memory 141 a, an imageformed under light irradiated through the green filter is stored in thegreen memory 141 b, and an image formed under light irradiated throughthe blue filter is stored in the blue memory 141 c.

[0475] When the infrared light transmission filter 111 b is insertedinto the path of illumination light, an image signal is stored in thered′ memory 161 a, green′ memory 161 b, or blue′ memory 161 c accordingto the position of the RGB rotary filter 165. In other words, afluorescence image is stored in the red′ memory 161 a or green′ memory161 b, and an image (background image) formed without illumination lightis stored in the blue′ memory 161 c.

[0476] The background image is represented by a noise derived from lightleaking in from outside the body and a stationary noise inherent to anequipment. The background noises do not pose a very serious problemduring normal light observation, but pose a serious problem when feeblefluorescence is observed.

[0477] In particular, light with wavelengths in the near infraredspectrum is well-transmitted by a living tissue because it is littleabsorbed by hemoglobin or water. When fluorescence with wavelengths inthe near infrared spectrum like fluorescence emanating from an antibodylabeled by ICG is observed, mixture of leakage light coming from outsidea subject poses a problem.

[0478] The two subtracters 162 and 163 subtract a background image froma fluorescence image, whereby the above background noises are removed.Two fluorescence images from which the background noises are removed areadded up by the adder 164. A resultant signal is input to theintegration circuit 142 having the configuration shown in FIG. 46. Anoise that is temporally unsteady is thus eliminated.

[0479] Signals output from the red memory 141 a, green memory 141 b,blue memory 141 c, and integration circuit 142 are input to the imageprocessing circuit 130, and subjected to image processing such as imageenhancement and noise elimination. The resultant signal is input to theimage display control circuit 131 and controlled for simultaneousdisplay of a fluorescence image, a normal light image, and characterinformation.

[0480] A digital signal output from the image display control circuit131 is input to the D/A conversion circuit 132 and converted into ananalog signal. The analog signal is then output to the monitor 105. Theautomatic light adjustment circuit 133 sends a signal for use incontrolling the illumination light diaphragm 112 so that illuminationlight of proper brightness can be irradiated. The timing control circuit134 synchronizes and controls rotations of the rotary filters, drive ofthe CCD, and processing of various video signals.

[0481] On the monitor 105, depending on the position of the spectrumrestriction rotary filter 111, a normal light image or fluorescenceimage can be displayed or both of the images can be displayedsimultaneously.

[0482] In this embodiment, the single lamp 110 is used as a light sourcefor observation. Alternatively, two or more light sources, for example,a halogen lamp for normal light observation and a laser orlight-emitting diode for use in exciting a fluorescent substance may beused in combination.

[0483] Moreover, illumination light for exciting a fluorescent substancemay be irradiated in vitro.

[0484] Moreover, the position of the CCD 121 is not limited to theposition in the distal part 117 of the insertional part 107.Alternatively, the CCD 121 may be incorporated in the processor 104D,and light may be introduced over an image guide fiber. Otherwise, theCCD 121 may be incorporated in a camera head attachable or detachable toor from an optical endoscope.

[0485] Moreover, processing may be carried out field by field instead offrame by frame.

[0486] This embodiment has the advantage described below.

[0487] Since a background image formed without irradiation of light issubtracted from a fluorescence image formed with irradiation ofexcitation light, a fluorescence image little affected by a noisederived from light leaking in from outside can be produced.

[0488] Next, the eleventh embodiment of the present invention will bedescribed. An object of this embodiment is to provide a fluorescentendoscope system capable of offering image quality, which is good enoughto permit easy observation and thus facilitate diagnosis, in eithernormal light observation or fluorescence observation.

[0489] A fluorescent endoscope system 101E of the eleventh embodimentshown in FIG. 58 is different from the fluorescent endoscope system 101Ashown in FIG. 31 in points that a light source apparatus 103E includes,in addition to the components of the light source apparatus 103A, a lamplight emission control circuit 153 for controlling glowing of the lamp110, and that a processor 104E has a variable preamplifier 166 whoseamplification factor is variable in place of the preamplifier includedin the processor 104A, has red, green, and blue memories 141 a, 141 b,and 141 c in place of the first and second frame memories 128 and 129,and has red, green, and blue spatial filters 167 a, 167 b, and 167 c inplace of the image processing circuit 130.

[0490] The spectrum restriction rotary filter 111 has the structureshown in FIG. 32, and exhibits the spectroscopic characteristics oftransmission shown in FIG. 33. The RGB rotary filter 113 has thestructure shown in FIG. 34, and exhibits the spectroscopiccharacteristics of transmission shown in FIG. 35.

[0491] Next, the operations of the fluorescent endoscope system 101Ehaving the foregoing components will be described.

[0492] A fluorescent substance having an affinity for a lesion such as acarcinoma, such as, an antibody labeled by ICG is administered inadvance to the examined object 119.

[0493] In normal light observation, the visible light transmissionfilter 111 a of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 113 is rotated 30 times persecond. Thus, red, green, and blue light rays are irradiatedsuccessively (See FIG. 49).

[0494] In fluorescence observation, the infrared light transmissionfilter 111 b of the spectrum restriction rotary filter 111 is locked onthe optical path, and the RGB rotary filter 113 is rotated 30 times persecond. Thus, infrared light with wavelengths in the spectrum ofwavelengths of excitation light is irradiated (FIG. 50).

[0495] In this embodiment, the mode of fluorescence/normal lightsimultaneous observation is not implemented in an attempt to simplifythe configuration of memories and reduce cost. The lamp light emissioncontrol circuit 153 gives control so that a current to be supplied tothe lamp 110 varies responsively to the change of positions of thespectrum restriction rotary filter 111. A larger current than a currentto be supplied in normal light observation is supplied in fluorescenceobservation, whereby the intensity of fluorescence can be increased.This results in a bright fluorescence image.

[0496] Reflected light and fluorescence stemming from the examinedobject 119 is passed by the diaphragm 152 for restricting an amount oflight and the excitation light cutoff filter 123, and then imaged by theCCD 121. The excitation light cutoff filter 123 is designed to cut offexcitation light components for exciting an antibody labeled by ICG andto transmit fluorescence components and visible light components. Theexcitation light cutoff filter 123 exhibits the spectroscopiccharacteristic of transmission shown in FIG. 38. The CCD 121 thereforereceives red, green, and blue visible light rays or infraredfluorescence according to the positions of the RGB rotary filter 113 andspectrum restriction rotary filter 111.

[0497] An electric signal output from the CCD 121 is input to andamplified by the variable preamplifier 166 in the processor 104E. Thegain of the signal is controlled by the AGC circuit 125.

[0498] The amplification factor in the variable preamplifier 166employed in this embodiment can be varied and is controlled with acontrol signal input over an external control line. The variablepreamplifier 166 is controlled synchronously with the rotation of thespectrum restriction rotary filter 111 in response to a control signaloutput from the timing control circuit 134. When the visible lighttransmission filter 111 a of the spectrum restriction rotary filter 111is inserted to the optical path (in normal light observation), theamplification factor is lowered. When normal light is imaged forobservation, since a relatively bright image is produced, a lowamplification factor will do. When the infrared light transmissionfilter 111 b is inserted (in fluorescence observation), theamplification factor in the variable preamplifier 166 is raised. With ahigher amplification factor, even a region from which feeblefluorescence originates can be observed at sufficient brightness.

[0499] Thereafter, the signal is input to the A/D conversion circuit 126and converted into a digital signal. The digital signal is stored in thered memory 141 a, green memory 141 b, or blue memory 141 c selected bythe multiplexer 127.

[0500] Based on a control signal sent from the timing control circuit134, the multiplexer 127 selects the red memory 141 a when the redfilter 113 a of the RGB rotary filter 113 is inserted to the opticalpath, selects the green memory 141 b when the green filter 113 b isinserted thereto, and selects the blue memory 141 c when the blue filter113 c is inserted thereto.

[0501] Signals output from the red, green, and blue memories 141 a, 141b, and 141 c are input to the red, green, and blue spatial filters 167a, 167 b, and 167 c respectively, and subjected to image processing suchas image enhancement (contour enhancement) or noise elimination.

[0502] The spatial filters 167 a, 167 b, and 167 c execute convolutionfor two-dimensional image data using a window of 5 by 5 in size. Each ofthe spatial filters 167 a, 167 b, and 167 c has a plurality ofcoefficient registers therein. Coefficients can be rewritten or changedfrom one to another in response to a control signal.

[0503] The timing control circuit changes coefficients synchronouslywith the change of the position of the spectrum restriction rotaryfilter 111. For example, when the infrared light transmission filter 111b is inserted to the optical path (in fluorescence observation),coefficients permitting smoothening of an image like the one shown inFIG. 59 are set. A fluorescence image that is unprocessed is affected bya noise because of a low signal-to-noise ratio. By carrying out thesmoothening, the fluorescence image can be viewed without the adverseeffect of a noise.

[0504] When the visible light transmission filter 111 a of the spectrumrestriction rotary filter 111 is inserted to the optical path (in normallight observation), coefficients permitting sharpening of an image likethe one shown in FIG. 60 are set. When normal light is imaged forobservation, a relatively bright image is produced. In this case, theimage is little affected by a noise because of a good signal-to-noiseratio. A sharpening filter enabling clear vision of even the microscopicstructure of a lesion will therefore prove effective.

[0505] Image signals output from the spatial filters are input to theimage display control circuit 131, and controlled for display, forexample, synthesized with character information. A digital signal outputfrom the image display control circuit 131 is input to the D/Aconversion circuit 132 and converted into an analog signal. The analogsignal is output to the monitor 105.

[0506] The automatic light adjustment circuit 133 sends a signal for usein controlling the illumination light diaphragm 112 so that illuminationlight of proper brightness can be irradiated. The timing control circuit134 synchronizes and controls rotation of the RGB rotary filter 113,change of the position of the spectrum restriction rotary filter 111,drive of the CCD, processing of various video signals, and glowing ofthe lamp.

[0507] On the monitor 105, either of a normal light image andfluorescence image can be viewed depending on the position of thespectrum restriction rotary filter 111.

[0508] In this embodiment, coefficients of each of the spatial filters167 a, 167 b, and 167 c are set so that the sum thereof will be 1.Alternatively, the coefficients may be set so that the sum thereof willbe larger than 1. In this case, the spatial filters 167 a, 167 b, and167 c are provided with an amplification function. Otherwise, thecoefficients may be set according to the position of the rotary filter111 so that the sum thereof will be larger in fluorescence observationthan in normal light observation.

[0509] A light source for observation is not limited to the single lamp110. Alternatively, two or more light sources, for example, a halogenlamp for normal light observation and a laser or light-emitting diodefor use in exciting a fluorescent substance may be used in combination.

[0510] Moreover, illumination light for exciting a fluorescent substancemay be irradiated in vitro.

[0511] Moreover, a means for controlling an amount of illumination lightis not limited to the mechanism for varying a current to be supplied tothe lamp. Alternatively, the opening provided by an illumination lightdiaphragm may be controlled or a filter for restricting an amount oflight may be inserted to the path of illumination light.

[0512] Moreover, the position of the CCD 121 is not limited to theposition in the distal part of the insertional part of the electronicendoscope 102E. Alternatively, the CCD 121 may be incorporated in theprocessor 104E, and light may be introduced over the image guide fiber.Otherwise, the CCD 121 may be placed in a camera head attachable ordetachable to or from the optical endoscope.

[0513] Moreover, processing may be carried out field by field instead offrame by frame.

[0514] According to this embodiment, the amplification factor in thevariable preamplifier 166 or an amount of illumination light iscontrolled responsively to switching of fluorescence observation andnormal light observation. It will therefore not take place that afluorescence image and normal light image are markedly different inbrightness. An object from which fluorescence and normal light originatecan be observed at proper brightness.

[0515] Moreover, coefficients to be set in each of the spatial filters167 a, 167 b, and 167 c are changed responsively to switching offluorescence observation and normal light observation. A fluorescenceimage is produced as an image little affected by a noise, and a normallight image is produced as an image showing even the microscopicstructure of an object clearly. Thus, the object can be observed usingan appropriate image.

[0516] Finally, embodiments constructed by combining parts of theaforesaid plurality of embodiments belong to the present invention.

What is claimed is:
 1. An endoscope system, comprising: an endoscopehaving an elongated insertional part capable of being inserted into aliving body; an administering means for use in administering afluorescent substance, which emits fluorescence with wavelengths in afirst infrared spectrum to be transmitted by a living tissue moreefficiently than light with wavelengths in the visible and ultravioletspectra, and which is apt to be accumulated in a lesion, to the insideof a living body; an excitation light irradiating means for irradiatingexcitation light with wavelengths in a second infrared spectrumdifferent from the first infrared spectrum to the living tissue insidethe living body to which the fluorescent substance has beenadministered; an imaging means, incorporated in said endoscope, forcutting off excitation light and producing a fluorescence image usingfluorescence with wavelengths in the first infrared spectrum emanatingfrom the fluorescent substance; a signal processing means for processinga signal output from said imaging means and producing a video signal;and a display means for displaying an image represented by the videosignal.
 2. An endoscope system according to claim 1, wherein saidfluorescent substance is an antibody labeled by indocyanine green.
 3. Anendoscope system according to claim 1, wherein said excitation lightirradiating means irradiates excitation light intermittently, furthercomprising a subtracting means for subtracting a background image formedby said imaging means when excitation light is not irradiated from afluorescence image formed by said imaging means when the excitationlight is irradiated.
 4. An endoscope system according to claim 1,wherein said endoscope is an electronic endoscope having said imagingmeans located in the distal part of said insertional part.
 5. Anendoscope system according to claim 1, wherein said endoscope is acamera-mounted endoscope composed of an optical endoscope having animage guide over which a fluorescence image is propagated and a TVcamera mounted on an eyepiece unit of said optical endoscope and havingan imaging device for photoelectrically converting the fluorescenceimage therein.
 6. An endoscope system, comprising: an endoscope havingan elongated insertional part capable of being inserted into a livingbody; a light source means for simultaneously irradiating excitationlight with wavelengths in a first infrared spectrum for exciting afluorescent substance administered to a living tissue, and light withwavelengths in the visible spectrum; a separating means for separatingfluorescence with wavelengths in a second infrared spectrum, whichincludes at least part of the spectrum of wavelengths of excitationlight for exciting a fluorescent substance and is different from thefirst infrared spectrum, from light stemming from the living tissue; afirst imaging means for imaging the fluorescence separated by saidseparating means; and a second imaging means for imaging light withwavelengths in the visible spectrum.
 7. An endoscope system according toclaim 6, wherein said fluorescent substance is an antibody labeled byindocyanine green.
 8. An endoscope system according to claim 6, whereinsaid separating means is a dichroic mirror, and said second imagingmeans includes at least three imaging devices different from the one ofsaid first imaging means.
 9. An endoscope system according to claim 6,wherein said separating means is a mosaic filter, and said first imagingmeans and second imaging means are realized with a common imaging means.10. An endoscope system according to claim 6, wherein said separatingmeans includes a dichroic mirror, and said first imaging means includesan image intensifier.
 11. An endoscope system according to claim 9,wherein said endoscope is an electronic endoscope having said separatingmeans and common imaging means located in the distal part of saidinsertional part.
 12. An endoscope system according to claim 9, whereinsaid separating means, first imaging means, and second imaging means arelocated in a TV camera to be mounted on an eyepiece unit of an opticalendoscope having an image guide.
 13. An endoscope system, comprising: anendoscope having an elongated insertional part capable of being insertedinto a living body; an administering means for use in administering afluorescent substance that emits fluorescence with wavelengths in afirst infrared spectrum to be transmitted by a living tissue moreefficiently than light with wavelengths in the visible and ultravioletspectra and that is apt to be accumulated in a lesion; an excitationlight irradiating means for irradiating excitation light withwavelengths in a second infrared spectrum different from the firstinfrared spectrum to the living tissue inside the living body to whichthe fluorescent substance has been administered; a visible lightirradiating means for irradiating light with wavelengths in the visiblespectrum to the living tissue through said endoscope; a first imagingmeans, incorporated in said endoscope, for cutting off excitation lightand forming a fluorescence image using fluorescence with wavelengths inthe first infrared spectrum emanating from said fluorescent substance; asecond imaging means, incorporated in said endoscope, for imaging lightwith wavelengths in the visible spectrum; a signal processing means forprocessing signals output from said first and second imaging means andproducing a video signal; and a display means for displaying an imagerepresented by the video signal.
 14. An endoscope system according toclaim 13, further comprising a control means for controlling the outputlevel of said first imaging means on the basis of an output signal ofsaid second imaging means.
 15. An endoscope system according to claim14, wherein said control means includes an amount-of-light control meansfor controlling amounts of light output from said excitation lightirradiating means and visible light irradiating means.
 16. An endoscopesystem according to claim 14, wherein said control means includes a gaincontrol means for controlling a gain to be provided by an amplifyingmeans for amplifying an image signal produced by said first imagingmeans.
 17. An endoscope system according to claim 13, further comprisingan image normalizing means for extracting a reference image depicted bylight with wavelengths or 600 nm or longer from an image formed by saidsecond imaging means, and normalizing a fluorescence image formed bysaid first imaging means relative to the reference image.
 18. Anendoscope system according to claim 13, further comprising a markerproducing means for producing markers to be displayed at positions in ascreen, which are determined on the basis of the luminance levels of afluorescence image formed by said first imaging means and associatedwith regions concerned, and an image superimposing means forsuperimposing the markers on a visible light image formed by said secondimaging means.
 19. An endoscope system according to claim 13, wherein atleast one color is assigned to a fluorescence image formed by said firstimaging means, at least one color is assigned to a visible light imageformed by said second imaging means, and the images are displayed onsaid display means.
 20. An endoscope system according to claim 13,wherein said first imaging means and second imaging means share the sameimaging device.
 21. An endoscope system according to claim 20, furthercomprising a diaphragm means inserted to an optical path linking theliving tissue and said imaging device, wherein said diaphragm means iscomposed of a visible light transmission area for transmitting visiblelight and a visible light non-transmission area that does not transmitvisible light but transmits light with wavelengths in the first infraredspectrum and that has a larger transmission field than said visiblelight transmission area.
 22. An endoscope system according to claim 13,further comprising a switching means for switching excitation light andvisible light and irradiating selected light to the living tissue,wherein the amounts of excitation light and visible light are controlledsynchronously with the switching.
 23. An endoscope system according toclaim 13, wherein an image signal representing a fluorescence imageformed by said first imaging means and an image signal representing avisible light image formed by said second imaging means are switched andthen input to said signal processing means, and said signal processingmeans controls the gain of an image signal synchronously with switchingof the fluorescence image and visible light image to be input.
 24. Anendoscope system according to claim 20, further comprising a switchingmeans for switching excitation light and visible light and irradiatingselected light to the living tissue, and a variable diaphragm meansinserted to an optical path linking the living tissue and said imagingdevice, wherein an amount of light to be passed by said variablediaphragm means is controlled according to the switching.
 25. Anendoscope system according to claim 20, further comprising a switchingmeans for switching excitation light and visible light and irradiatingselected light to the living tissue, and an integrating means forintegrating a current level of an image signal produced by said imagingdevice and a level thereof attained during an immediately precedingframe, wherein weighting that is the integration is controlled accordingto the switching.
 26. An endoscope system according to claim 20, furthercomprising a switching means for switching excitation light and visiblelight and irradiating selected light to the living tissue, whereincontrol is given so that: when an image signal representing afluorescence image is output from said imaging device according toswitching by said switching means, the image signal is passed to afilter circuit responsible for smoothening; and when an image signalrepresenting a visible light image is output from said imaging device,the image signal is passed to a filter circuit responsible for contourenhancement.
 27. An endoscope system according to claim 13, wherein saidexcitation light irradiating means and visible light irradiating meansirradiate light output from a lamp, which glows in a spectrum includingthe first infrared spectrum and visible spectrum, as color sequentiallight to the living tissue, because a first filter and second filter fortransmitting light with wavelengths in two spectra within the visiblespectrum, and a third filter for transmitting excitation light withwavelengths in one spectrum different from the two spectra within thevisible spectrum and in the first infrared spectrum are arrangedsuccessively on the optical path.
 28. An endoscope system according toclaim 27, wherein said signal processing means produces a video signalrepresenting a fluorescence image during one frame required forproduction of a video signal representing a color image of one frameunder irradiation of color sequential light.
 29. An endoscope systemaccording to claim 13, wherein the excitation light and visible lightare irradiated simultaneously to the living tissue.
 30. An endoscopesystem according to claim 29, wherein said first and second imagingmeans can simultaneously produce a fluorescence image and a visiblelight image depicted by light with wavelengths in the visible spectrum.31. An endoscope system, comprising: an endoscope having an elongatedinsertional part capable of being inserted into a living body; a lightsource means for irradiating illumination light containing excitationlight with wavelengths in a first infrared spectrum which causes afluorescent substance to be administered to a living tissue tofluoresce; a first imaging means for producing a fluorescence imagedepicted by light with wavelengths in a second infrared spectrumdifferent from the first infrared spectrum of wavelengths of excitationlight for exciting a fluorescent substance administered to the livingtissue; a second imaging means for forming a reflected light imagedepicted by reflected light of the illumination light stemming from theliving tissue; and a display means for displaying the fluorescence imageand reflected light image formed by said first and second imaging meanswhile superimposing the fluorescence image on the reflected light image.32. An endoscope system according to claim 31, wherein said secondimaging means forms a reflected light image using reflected light ofexcitation light.
 33. An endoscope system according to claim 31, whereinsaid second imaging means forms a reflected light image simultaneouslywith a fluorescence image to be formed by said first imaging means. 34.An endoscope system according to claim 31, wherein said display meansdisplays a fluorescence image and reflected light image in mutuallydifferent colors.